Definitely check out Heath Diesel, really good guys
The 5-speed is a good swap for the over drive & beings how you do actually tow something with this, the manual trans want be a problem (I just didnt know if this was a in town putter or a hauler)
For going 85 you are prolly gonna want something taller than 373's so it may not tow that great... There is a fine line there & you just have to decide which way you wanna go
The bigger injectors is a good deal, infact Heaths big injectors are pretty good
One thing you REALLY need to do to this engine, is get a 96 & later (IIRC) cooling system, they made a lot of changes to it & without it you will most likely over heat it
Also tell Bill that Lee Parker recommended you
He can help you with keeping this thing going & preventing some common problems with them
Im not saying that they are "bad" engines, just not Uber powerful