Dont know what to do!!??

[87 GMC]

I have an 87 GMC and a 89 Chevy, the 89 is my daily driver, I want something else to drive so I can work on the 89, I can drive the 89 and work on the 87 to make it a daily driver. Heres the problem, the 87 needs a motor, its got a TBI 262 in it, would it be cheaper to put a 350 in with a carb or go back with the V-6 and TBI? What would the gas milage diff be? The trans is a rebuilt TH400 with under one mile on it. My question is do I fix the 87 so I can drive it or sell it for the money to work on my 89? How much would it cost to put a motor in the 87? The 87 has a perfect rust free body and no dents but needs to be painted and it only needs a dash pad to be perfect inside, maybe some better looking door panels or just paint them. So is the 87 worth keeping and fixing? Thanks