Alan, I sense that you have the 'bit between your teeth' on this one, but I'm inclined to agree with 'L.S.' in his more cautionary approach. As a rule, car engines, on account of, as you said yourself, their lower RPM and more efficient cooling and lubrication systems than their motor-cycle equivalents, do not normally require a bottom end refresh as frequently as I suspect do bikes.
Whilst I'm also very much in favour of preventative maintenance, a case might also be made for 'if it ain't broke, don't fix it'*. On that basis, it could indeed make sense just to replace the rings and shells and leave the big job until later.
I don't have your degree of experience with bikes, being limited mainly to mopeds, scooters and other low capacity machines like the BSA Bantam, but I can remember a time when the need for a top-end overhaul every 10,000 miles was not unusual, with a rebore, new pistons, reground crank and new big ends and mains at 30. Certain cars, like the Riley, didn't even use shells (although a conversion kit was available) but used fragile white metal bearings which required recasting and line-boring.
Regards, John.
*As an aside, a 'bus operator that I knew took preventative maintenance to a whole new level. As part of a national policy, they introduced an 'Annual' service, a requirement of which was to routinely replace all of the vehicle's coolant hoses. Accordingly, OE hoses, which might be expected to last for at least three years, were cut off vehicles - some little more than a year old.
These were replaced with after market items of an inferior quality (to save money (!)) which were found to have a MTBF of 10 months! It was not unknown for one to fail in service, only to be replaced, and cut off and renewed again, a couple of months later, when the vehicle came in for it's 'Annual'.
J.