Towing with a small block

[kwmech]

So my 91 Suburban has the anemic 350 TBI engine with about 160k on the clock. I've done gearing upgrades along with swapping to 1 ton axles and 4.56 gearing, along with that is going to a 4l80e with a stand alone controller. Was thinking of going with a stroker kit. I see locally somebody selling a 94 suburban with a 454. It would totally bolt into my squarebody and all the parts are there for the conversion aside from having the exhaust cleaned up. 454 has about 50k on it while the whole 94 burb has 180k on it. Don't know the specs off hand on the 94 big block, but I know I'll get probably twice the amount of torque I need, but the mileage may really fall off. However at the same time the mileage on the 350 isn't all that great toting this aerodynamic brick around with another brick behind it. Thoughts?? An Ls conversion is really not in the cards being california and smog nazis I'd have to deal with.