I adapted a junk yard HEI to my GMC 6 many years ago and it is still working great. There was a noticeable improvement in engine starting and performance. I had to modifying the HEI mechanical advance curve (no vacuum connection) to mimic the old GMC/Chevy curve. The GMC and old Chevy 6s advance evenly from 10 to about 38 degrees at 3000 rpm, where they level off. The HEI advance is limited to about 20 degrees - 18 degrees less than needed. I assume the 292 would like 38 degrees advance too.
I followed the instructions given by:
http://www.boyleworks.com/ta400/psp/distcurve.html. It took a lot of trial and error to get the advance profile close, but it worked out well for me. The advance kits should do the same.
