My choice would be the 235,the SM 420 and an open drive rear end to start with. Depending on how much you plan to haul with your truck,you could remove a leaf or two from each spring and install some good shocks to make for a better ride. It'd be good to convert to a newer design master cylinder,for safety sake.You might freshen up the stock front end;kingpins,tie rod ends and drag link if it needs 'em. Keep in mind with the exception of the engine swap,these are all good weekend projects,making the truck driveable through the week. If you decide you want to change your mind on any of the mods you do,you can often sell the parts you change for enough to help cover the next project.
I wouldn't be inclined to go the V-8 route,they're a lot of work to install properly,harder to work on,and an eight powered stovebolt just doesn't get the admiration a clean six powered one gets.
Later on,if you decide the rear end ratio you swap in isn't tall enough,a T-5 will be relatively easy to install with one of the kits available now.
The key is to not jump into a big bunch of conversions all at once;it'll eventually overwhelm you,you lose interest,end of project.Try to prioritize what you want to improve and do it a section at a time. That way you can enjoy the job,always see the light at the end of the tunnel,and know it won't be long before you can drive your truck again.
Have fun with it.
Speed
