Which engine to get?

[jorgensensc]

Hey guys,
It's been awhile since I have been on here, you know, life took over. So here is my question:
I've got a 72 3/4 ton suburban with the big block. Runs great, but gas mileage sucks (6-9 mpg). Soon going to be my daily driver. So I'm looking into an Lsx swap. I've been trying to read as much as I can, but it's to a point now where there is so much info, I can't figure out what's what anymore. Here are my options:
2011 5.3 with 500 miles, already has stand alone harness and PCM with mag and pedal. Mated to a built th350. Price: 2500.00
2006 6.0 with 70k miles with harness and tranny and PCM and pedal for 2500.00
Which would you get if you had the choice? Should I get the overdrive tranny? Will the 3 speed really hurt mpg that much? Will the th350 hold up to the weight of the suburban?

Also, let me see of I understand everything else I need for the swap:
Fuel pump (walbro)
Fuel regulator (99+ c5 vette)
Motor stands ( which ones are the best, and will work with my 3/4 ton frame?$
Exhaust work
Which exhaust manifolds did we decide work?
Sanden AC compressor brackets (already have vintage air front and rear)
Power steering hose adapters (where to buy from)
Electric fans (I thought there were some that mounted to the stock '72 4 core radiator?)
Tranny mount ( buy new or adapt my th400 crossmember?)
Driveshaft modified
Anything else I'm missing?

Thanks for the help guys!!
Posted via Mobile Device