Turbo the 454 or LS?
 

So I've finally grown a pair and decided to turbo my car. Currently it has a stock 454 with peanut port heads that I swapped in a couple years ago. I should have a 4.8 LS at my disposal here shortly. Which do you think will respond better to boost? I know there are what seems like thousands of threads and magazine articles about the LS motors and how they love boost, but a 454 is a 454. Will the LS hold up to more boost than the big block?

At first I don't want to push more than 10psi just to create a fun daily driver, which on either motor should accomplish my goal. I also don't want to tear down either motor just yet, so 8-10psi is about my ceiling. I would like to keep my land speed record 2.28 gears, at least for now. The car is on propane with an OHG 450 and I think a blow through setup is the way to go. So I have a few noob questions, of which I have tried to find the answer to without much luck.

What options do I have for junkyard turbos that would work well?
Do I need to worry too much about top end power on this 454 that will never see over 5000rpm anyway?
Diesel turbos on the 454?

Any input is appreciated!

It depends on your goals. Both can definitely be boosted, but they're going to behave very differently. A 4.8 is going to be a high RPM screamer, while the 454 (particularly if it's on the stock cam) will be a torque monster with less top end.

The 4.8 will have better part availability for boost. Plus the compression ratio will be more favorable for boost as well. What fuel system do you plan on using? The 454 would be sick, but I bet you have to fabricate more parts for it.

I plan to use the propane mixer I have, or possibly track down a second if I need more fuel. The 454 is a 79 so compression should be pretty good at about 8:1. And I'm totally ok with fabricating parts. The more parts I can build the less I have to spend!

So working with the numbers/forumlas in he sticky about turbo selection, I've come up with the following for the 454 (with a 5000rpm peak.) Most of the numbers used in the sample work for my application @ 10psi and ambient air temp.
(454 x 5000) ÷3456 = 656CFM
(656 x .85VE) = 560CFM
(560 x 1.37DR) = 765CFM Actual inlet CFM
(10 + 14.7) ÷ 14.7 = 1.68:1 pressure ratio
(765CFM x .069) = 52.785 lb/min

So 53lb/min on a single turbo, or 26.5lb/min on twin turbo. Does this look right?
Now I just have to learn how to read a compressor map.