Ken, yes the Pertronix unit will fit under the stock cap. All you have to do is remove 2 screws, pull the points & plate, and put in the new one with the new screws. You have to run the new wires too, but it's easy as pie. I pulled my Accel 8.8mm wires off my 327 and used them on the 250. They're kinda long, but the work.

BTW, is there a "correct" way to install the rear oil pan seal? My 250 is leaking like crazy.

Thanks for the help.

'68 C-10 - 250 with Edelbrock 600cfm 4 barrel, Offy intake, Hedman headers and true duals, HEI, MSD 6A box, relocated gas tank
Soon to have: T-5 tranny