you really cant compare an old 350/307 with a newer tbi engine, that 6cyl probably has more power than both. the 350 even more so, it had enough torque to pull my 6000 pound camper comforably through the hills of PA in august from Maryland where i bought it, complete with stock 3.08 gears.

As a guy with many many trucks i can tell you that my 85 with a 350 is much less powerful than my 93 was when its 350 was stock..It still has loads of power sporting a 4 spd manual with 4.11 gears and my 93 better known as bubba now with 4 spd auto and a 3.42 rear..its hard to compare them side by side due to the diffrent trans/gearing andsizes//33'* againts'36'* yet if you compare the engines i would take a 1993 350 (lo5) over a 1985 (LM1) the LO5 sports stock 210 hp and 300 tq and in my truck got 18-19 hwy
the LM1 sports 190 hp and around 280- 290 tq..and being carberatued mileage is much less.If i were you id go get a LO5 out of a 1993 plus silverado with harness and computer and swap that in you will be pleased..