Whilst i agree to a point my main objection to 'just fitting another t/s bearing' is that
yo only get two undersizes and very often the crank only needs a couple of thou to
bring it back to round. Re-lining the steel backed bush is the best way but takes a while.
I tend to agree about the line boring with the proviso that the bush housing has not
been flogged as they very often are after running with a knackered bush for a long
As the 2 case halves have only a single dowel it's normally possible to move them
around anyway so the bearing alignment is never that brilliant. Plus, as you bolt
the barrel down, unless the faces are spot on (which they seldom are) that will move
things as well. This is the case on lots of makes not just beezer. As an example i've just
put a replacement cam in an a65, you couldn't turn it without the cases being bolted
together all round and the barrel nipped down. Once done, it turns beautifully. The
crank has a needle race main so that ran nicely anyway.
Don't rely on the timing side area being flat or true, the parting faces are the ones to work from.
The cases move around all over the show as they heat up and cool down anyway.