I was always told if I was going to do any of the old series Mazda motors up, go the NA.
Shorter stoke means more revs.
From my engine manuals:
1600 - NA Bore - 78mm(3.07 in) Stroke - 83mm(3.27 in)
1800 - VC Bore - 80mm(3.15 in) Stroke - 88mm(3.46 in)
2000 - MA Bore - 80mm(3.15 in) Stroke - 98mm(3.86 in)
I've seen a few 808s with MA motors in them but with the extra height in the block
the standard airfilter no longer fits when the bonnet is closed. They have then fitted the
"snorkel" type airfilter assemblies from the early model HB 929 with MA motors, that
remote mounted the airfilter towards the inner guard.