4g64 swap into my 86 G54 pickup

[Pengineer1]

My 1986 Power Ram pickup runs fine, i rebuilt the motor during our Covid vacation, I put the 38 Weber carb on it and have Hooker super comp headers on it. Yes it's 4wd, 5 speed manual.

I found a pickup cab complete with motor, 5sp 4 wheel drive transmission and driveshafts. It has a 1991 4g64 motor. It was supposedly rebuilt before somebody chopped the bed and frame off to make themselves a trailer.

So please give me all opinions or experiences or advice you may have about me removing my perfectly good 2.6 liter and swapping in this unknown 1991 4G64 .

I'd like you to tell me I'll get better MPG and better horsepower and even better reliability with the fuel injection... but I don't want to assume it hope for that and later find the swap wasn't worth it.

Should I expect that the gearing of my 86 rear axle should match the gearing of the 91? Or should I just swap motors and keep my transmission in place??

Thanks again, guys, in advance. You've always been so helpful through the years and this feels like a big project I might regret?!??
Bill

[Pengineer1]

Is the 4G64 an improvement over the older G54b carburetor motor? Better power? Better gas mileage? Longevity? Even if you may not have personal experience doing this swap I'd appreciate any opinions or ideas. Thanks in advance! Bill