I don't know how comfortable you are with electricity, but I'd suggest first doing the negative-ground conversion, then when everything is working, do the alternator conversion. Doing things one step at a time prevents a lot of problems.
As for the alternator conversion, I'd do a little research on-line, find out which alternators fit well, and do the conversion without a kit. It will save a lot of money. I did this with my Bugeye Sprite; it was easy and worked out well.
https://www.nonlintec.com/sprite/alternator/