The roller cam and Duraspark isn't a problem, just run to your local parts house and ask for a reman 85 Mustang distributor for a manual transmission car. It will be a Duraspark distributor with a steel cam gear for the roller cam. Advance Auto Parts sells these for $55 with a good core to trade in. Doesn't have to be the same core, just a core.
You will need the small flex plate unless you have the bell housing for the 164 tooth flex plate. Most Comet and Mavericks are using the 157 tooth flex plate that comes from the factory. The 250 uses this flex plate and conveter although the six's flex plate is not balanced for the V-8.
so me and sam exchanged PM's. it sounds like he has a pretty healthy complete '77 maverick engine. i'm probably gonna go pick it up. at the very least i'll be able to use it as a parts engine.
excellent advise !!!!! that dist. also has a excellent advance curve...the FMS steel gear for roller eng. conversion alone cost me 60.00 USD from summit.