Greetings from FINLAND.
Guy`s allready tell you almost all important facts, but there is possibilities to build B-20 eaven 2.7 litre. It costs ofcourse. But reasonable swap is use 74-75 Block dia 93mm using B21 ET:s pistons, and take off material to the top, how much, it depends the stroke, etc. We have welded cranks or take off just other side, and make 84mm stroke. It is necessary to " nitro" them but the realibity is of course weaker.But some guys drive those in street. Rods are quite strong, if you take the "M" its forged by BOFORS, there is letter side of the rod. Those "thick" rods (B-21) are weak, as you had been told. However my friend has raced cross 3 years whith same engine, just opened it once of year, new piston rings, rod bearings just to be sure. Main bearrings are same. Power has taken out 246 bhp 7600 rpm . capacity 2490 ccm. If you want more info in net : UNITEK ST Luleå, SPM-Motor ( Sten Parner ) or TIMO`s Motor ( Timo Kormu ) All has several Gold Medal engines since 60`s. Best VOLVO regards to all quy`s.

Yrs: WEBERMAN /A.M.O.Ylander