Will '78 dist. work in '76 I-6?

[Shell]

Helping a computerless friend from across the country upgrade his ignition w/TFI parts. He's got a '76 CJ-7 w258. I was wondering if he can get a junkyard distributor base for a '78-'86 258 and drop it in so we can do the TFI upgrade. I believe one of the main differences in the dist. models is how the caps attach. Are there other issues such as shaft length or dist gear size?
I've done this upgrade on my 258, along w/Nutter bypass and I'm happy with it. If someone could let me know about this interchangability thing, I'd sure appreciate it. Thank you for your time.