Ditto! I was set to have a monster TH400 built for my '71 back in the late 70's, and the transmission guy I talked to talked me out of it. He said I'd lose a little power turning the heavier trans, and that he could build me a TH350 that would work and hold up behind my 427, even in drag race conditions. The rebuilt TH350 he built for me back then saw many 1/4 mile passes, and is still in the '71 today, and still working fantastic.

 

Even a run of the mill TH350 with a shift kit is fie for most.

The guy asking about the water pump. I dont think it can be done without using the Optidrive type water pump. There are reverse rotation and reverse flow, dont confuse the two. The reverse rotation is for cars with serpentine belts. The belt rotates the water pump backward but the coolant runs on the same path as before.

The reverse flow, flow the water backwards through the engine and have some many hoses I dont ever care to figure it out. The LT1 heads arent any better than a Vortec head. I think they are the same design in the runner and chamber area. I wouldn't hesitate to toss those on an engine though. I have never looked at a LT1 gasket so I couldnt tell you what the difference is.

 

You don't have to make the cooling system reverse flow when using the LT1 heads on a gen1 block. That's an LT1 engine characteristic. You do need to block off (tig weld) a water passage that is in the lifter valley, or your oil will get awfully watered down! You also need to hook up external thermostat housings to the end water connections (factory crossover tube). You also need to use a LT1 intake manifold, but carburetor versions are available for around $300. Yes, the Vortec and LT1 head designs are very similar, but the LT1 comes out ahead for being aluminum. The LT1 heads can be a good cost alternative, and be better than other aftermarket aluminum heads.

 

If you can TIG.

 

One procedure is to fab a small rectangular aluminum chunk that's a wedge fit into the passage, then take the heads to a machine shop (if you can't tig) where they can weld it up and take a kiss cut off the surface of the head.
Cost of used LT1 heads + valve work + weld and a shave = still way less than aftermarket heads.
What could cut the savings down a little is if you already have a gen1 style intake manifold you planned on using. You would sell that and buy a new intake to fit the LT1 heads.

 

To save a lot of time and energy and one heck of a lot of money just get a set of Vortecs casting 062 or 906 and just go from their.

 

I don't know if what little you save with the Vortec heads would be worth it. With using a higher lift cam, the heads need to be machined to prevent spring bind. Also, the Vortec also takes it's own style of intake manifold. After that, you still have iron heads. Of course, if you're anti-aluminum, the Vortec's would be a consideration.

 

I wouldn't use Vortecs simply because of the limited variety of choices in intake manifolds from the aftermarket.

 

Not sure what you mean about limited??? Edelbrock makes intakes from the lower performer on up to the air gaps and ultra high RMP for racing. GM has several in there aftermarket book from street to strip or roundy round. Mercury Marine has both aluminum and cast in both 2 and 4 barrel setups. If you want to run vortecs on a TBI motor their are intakes for that to. If you want to super charge a motor their are intakes for that also. As they say its the best high performance factory iron head GM ever made.