I am looking for right around 400hp and i know both of these motors are capable of it. Does anybody know how much more the 383 would cost then a 355 because of all the machining and clearence issues? Also are there any clearence issues on the 355 that I should know about? Any thoughts or opinions at all would be greatly appreciated.

 

Correct me if I am wrong, but doesn't the Chev 305ci already have a 3.48" stroke?

The 350 Chevs are a 4.0" bore while still retaining the 3.48" stroke, I guess so they can use the same crank. This means that you should not have any clearancing issues with the crank, but to get a 4.0" bore you need to bore out 0.260" which is alot.

Will the 305ci block go to a 4" bore without hitting the water jackets or did the 350 use a different block?

As for 383, they generally use a 3.75" stroke with 4.0" bore - so you will probably need to clearance for the crank, but you have the same problem with the small 3.74" bore.

 

The extra cost will depend on your local machine shops really. For my build the 383, adding in the extra cost of parts, was only about $250 more than just rebuilding my 350 with the same performance parts. I highly doubt you are wanting to bore a 305 out to a 350 because that would NOT work. You will need a 350 block, a 305 block wouldn't be capable of surviving that much of a bore. 350 blocks are fairly cheap, so don't take a risk with a 305.
You do have to clearance the block for the extra stroke of a 383 if you decide on that, but you can do that yourself if you so desired.
The 383 will be more driveable at 400 horses than the 350 because of the extra stroke, so if you plan on driving it alot then go 383. The 383 also makes power easier and has more torque than a 350. I see it as the better choice, but it's a matter of preferance really.

 

sorry forgot to add that i have a running 350 block out of my dads old truck that he doesnt drive anymore i was gonna tear it down, and redo it since its sat for about 5 years. the 355 is a .030 bored 350 and the 383 is the 400 crank and bored.

 

^ good, trying to bore out a 305 wouldn't be the best idea. I would go for the 383. Even though it's a little more expensive you'll be happy with it. It's easier to get the power you want out of the 383, which means you can drive it more often.
My blazer has a 383 that's making roughly 375 horses, with stock 64cc heads and it still uses a stock torque converter and drives fairly well. With aftermarket heads it would be at or above 400 no problem, so that just give you an idea of what you'd be looking at. My cam is somewhere in between .460-.470 lift.