how does stock 1990 fuel injection for a 351w work... to each piston seperatly? or front half back half ?

and will it work with a 302 motor?

 

I believe the trucks were batch fire, divided into left bank and right bank. A 351w fuel injected system will be calibrated for the larger 351w. A 302 will probably run, but not very well.

 

how hard is it to change the computer if it does run badly

 

Check the injectors to see if they are a different color. I am not sure, but the 351w might have had larger injectors, which will throw everything off a little bit. You could also go to www.partsamerica.com and pretend to order injectors for each vehicle and see if they are the same part number.