Ok I fixed the problem and it purrs at 500 rpm and no backfires at higher RPM
One thing was had gas pedal rod was stuck a little bit so always engine was running at higher rpms, fixed that and reset TDC, adjusted the timing with timing light not by ear. Then adjusted carb idle and air now it runs good.
Just to add note, 216 motor flywheel and bellhousing timing marks works good for 58 235 motor as I did a swap. They are all same since lot people said the timings may be different but today I set the timing with timing light and marks worked good
Sprayed carb cleaner no leakes around, put the vacuum gauage to wiper and showed in green zone in ~20 inches range.
Thanks for all the support help and you guys are awesome
Ganesh
