18R, 20R and 22R all have interchangeable distributor internals.
So converting between them is just a case of pulling them apart and reassembling one with the best bits.
I would not recommend going back to points for a race car.
I did that once when my igniter module died and my 8000rpm redline engine refused to go above 6000 due to points bounce.
EI rules !
My guess is that you wired it up wrong and burnt out the igniter.
Compare with the ei.pdf and points,.pdf diagrams here:
http://autos.groups.yahoo.com/group/...ng%20diagrams/
Or you can send me some photos of how you wired up your igniter and I will compare against my 1977 18R-G igniter.
- Stepho