Advice for Honda vf750c magna

Taken on a project bike to customise for myself, no time limit. She's an '83 model. Engine naff. I would like to replace with same lump but getting hold of a decent one seems pretty hard here. I can pick one up in uk but transport cost has to be added....so here's a question,
anyone know if I can put in another lump that might be more modern? I can change engine mounts myself and weld in new ones. I would prefer to change from shaft to chain so would need to replace the rear swingarm...mainly because I prefer a disc brake for rear and chain drive. I have quite a bit of knowledge on bike repairs and the workings of same so do not need to be treated like a muppet....but not a great deal on customising them. I like the front end but would prefer the rake to be slightly changed which I am prepared to pay someone to do, as I do not have a jig and am not going to build/buy one...but saying that I do not want to pay o.t.t.........who does? So I think you have the idea of my needs, but all said and done, if I could pick up another lump which is the same I will take, so if anyone knows of one going I would be gratefull if you let me know....it will save me quite a bit of work.
Please be sensible with your replies....if any.