replacing the engine

I recently acquired my grandfathers Ford F-1, it has spent the last 38 years in a leaky shed. The body is in pretty good shape, a few dents and some rust but nothing that can't be taken care of. The truck has a in- line 6 with a 3 speed manual transmission. I would like to pull the existing eng, trane and rear end and replace with a new or factory rebuilt 302 or (in-line 6), 5 speed trane and a 9" rear with 3:50 gearing or? I also plan to replace the front brakes with disk brakes. I do not want to lower it, would prefer to lift it a little so could put 18" tires and wheels on it. Can you please provide some guidance, wisdom and your thoughts? Thanks