You can easily install a 5.0 with all the original 68 external features, brackets, pulleys, valve covers, radiator, etc. You could do the whole deal before lunch.
i had a ford distributor with my 289. i added pertronix a while back, and had a good cap/rotor.
when i got the 5.0 (all stock long block), i knew i had to change the gear since i now had a roller cam (induction hardened).
some places sell a bronze gear, but ive heard from many reliable sources that bronze is not good for street cars since the gears usually dont last more than 5-10k miles.
the original 5.0 gear is .530" which wont fit the 289 dist., so i had to buy an MSD gear that matched a .465" shaft. When installing the new gear, you have to use a bigger dowel pin hole. the gear was a slight different shape, so i had to lower the hole location to maintain the same gear alignment. i used an indexer to rotate the new hole 90degrees.
with that said, you may just want to pay a machine shop 20-40 bucks to have them do it for you.