what motor would you turbo?

I'm planning out a turbo for my 74 club cab dually.

Automatic. Will be used for regular driving, and some hauling.

The truck is set up for a big block already, and I have 2 motors that are prime candidates.

Both are stockers, unmolested, and run awesome, with no smoke or ticking. Kinda cool.

1)76 400. it's out of a cordoba/charger. untouched, with the tq still on. 452's yadda yadda yadda

2)69 383 2bbl. Also untouched, 906's, and runs smooth as glass.

With eiher one, My plan was/is to leave the motor as stock as possible. Basic intake and carb change to match the turbo. A small turbo for quick spooling(torque is goal more than all out power). Intercooler to keep it from pinging under load, etc..

My debate is, does the larger displacement of the 400, and lower compression ratio, make it clearly more desirable for this build?(I agree it should make better power) OR does the steel crank and the still pretty low comp a 2bbl 383 has make it the better choice?

Both are in mine already, so there is no money involved.

I'v measured 400's to typically be around 7.5:1 compression. I measured a 68 2 bbl 383 once, and it was on the low 8's, so I would expect this 69 to be similiar.

Any input appreciated

I'd probably build the 383, just for the crank. I built a 318 instead of a 360, for the same reason. The little bit more compression may help the truck with pep at low RPM's as well. 7.5 is really low, even for boosted applications.

Put a performer on it with a 650-750 DP, blowthrough mod it, mild camshaft, surface the heads and use good gaskets. Theres a guy on theturboforums (and maybe here?) that goes by CW25 that did something pretty similar I believe.

400 has lower comp & bigger dia. pistons.It also has better heads(452).906s need to be ported & hard seats installed.both have cast pistons.steel crank does not matter because you are not going for max boost with cast pistons.No detonation,this will kill cast pistons.

I would build the 400 for the same reasons as above.

400.

Boost the 383 now and use the 400 for a real build! Strength is moot for a low boost application. The 383 might provide better non boost drivability with more comp.

Get the correct size turbo and there will be very little turbo lag.

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400 has lower comp & bigger dia. pistons.It also has better heads(452).906s need to be ported & hard seats installed.both have cast pistons.steel crank does not matter because you are not going for max boost with cast pistons.No detonation,this will kill cast pistons.

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How much difference are the ports between the 452's and the 906's?
Well, I'll tell ya...there's not enough difference between the ports of the two head to worry about but the good part about the 452's is that they have the hardened valve seats already...not that I ever sunk a valve in 906's.