I have a 67 Rs/Ss that has sat for years. I found a restoration shop to use. I plan to daily drive the car. I do have front end damage. I’m sure shocks and everything under the car is original. I was thinking about just buying a frame kit with suspension brakes the works. It is 13k but could be worth it instead of piecing together everything. I was wondering if anyone has done this and their experience with it. I am planning on dropping in a crate engine 350 with 500 hp or 572 yes I know the 572 would be overkill but thinking of options. Hopefully going to keep trans after the swap. Interior and backend panels are still in great shape. So at least I have that going for me. I want to spend 50k or less but we will see what happens. There are so many options before I buy parts I’m wanting to narrow down a solid plan.

 

Is the existing frame straight? If not, it may make sense. What you call piece together I call make it the way you want it. Matching brakes and a well thought out suspension is more important than the easy of just slapping a new sub frame in there. What I am saying is if I was spending that kind of money I would be buying complete suspension and brake setups for the whole car not buying a complete front end then try to match that.

Couple of other thought. Unless this was a 375 HP 396 it may have a M20 4 speed, that is a good box but not good enough to handle even the stock 375 HP/415 foot lb of Torque. The stock 12 bolt can handle up too 500 lb. but your rear springs will not. The stock 375 hp 396 was tested and sold with Bias tires. They did not have the traction of a radial tire. Radial tire have gotten much better since the early 70's when they were first released. Long store short, even if the whole car was stock and you put modern tires on it the whole rear end would jump up and down and try to shake the car a part. Especially a 67 as wheel hop was a problem with the bias tires on big block cars. As you know these cars have been around for a long time. There are fixes for everything. Of course you can fix the wheel hop and just about any torque range. Now you are into the fact that the car body itself is prone to twisting. So you will need weld in frame connectors and in the case of the 572 a roll cage to give the body enough support.

500 HP 350 as a daily drivers? You are talking about a fuel injected system aftermarket heads and tuned as a complete setup. I would want it in writing that it would be streetable with a manual transmission. GM built some high HP small block and even brand new it was really hard to call them streetable. You are talking about engines that idled around 1300 RPM and had almost no power below 2000 RPM. You would have to let the clutch out a 2500 RPM and even than the motor is not going to be happy, expect chuging.

572 is a big boy with a lot of torque if you really want to use most of that power you are talking about a lot of non-GM parts. There are no parts from the fan to the back wheels that I can think of that would be the same part that was used.

Are you really sure this is the way you want to go with number matching RS/SS

IMO, assume you have the title sorted out.
Sell the numbers matching RS/SS for 20k+ Buy a rust free shell for 12K, Get a LS3 motor and a T56 trans with a 9" inch rear. 430 real usable HP that you can take on a trap across the US over mountains and through deserts. It will not miss a beat and your lady can fall asleep in the passengers seat. If you are absolutely sure that 430 is just not enough HP then go for the LS7. That is a modern 427, That is a 500 HP motor is you buy a good used one out of a 06 Z06 Vet. I am told getting them to 600 hp with just a CAM upgrade and tune is possible. All in a motor 100lbs lighter then a small block.

Just a FYI. Many guys when building their first car say they want the most horsepower possible. Most people do not have the budget to do it but sometimes guys have deep pockets. Customer is always right and they get it built, they perform as expected at the track. A year later they are swapping Cams and detuning the motor because the customer realized they were not racing every weekend and wife/girlfriend or kids did not even want to ride in the car.

 

it's a far restoration point to start a project ! best of luck