X2, an 871 is not big enough for a 540" motor, just not enough volume. Maybe a 1271 and you could run your distributor in the stock location without an offset drive.
Don't know if you guys heard or not, but Mert Littlefield passed away 2 weekends ago. I've know him for over 25 yrs, i think it was due to a heart attack.
RIP Mert.
Zip.