Interesting! Certainly the early B21 used a flat faced flywheel with the later 8 bolt fitting. Part numbers needed though.
Dense but interesting reading here
http://people.physics.anu.edu.au/~am...ch_upgrade.htm
Also
https://www.brickboard.com/RWD/volvo..._flywheel.html
http://forums.swedespeed.com/showthr...crank-question
http://www.turbobricks.org/forums/sh...ad.php?t=13877
Will post a question elsewhere...............