['68OrangeSunshine]

Hi BigRig-- I'm not positive, but I think the flywheel off a 292 will fit the smaller L6s. 292s came with 11" flywheels like SBCs. Possibly 230s and 250s came with 10.5". As long as you use the bellhousing that was on the 292 and the clutch and frix disc fit I'd guess it's OK.
Motor mounts: the passenger side 292 tower is different, the drivers side is the same. The passenger side mounts from a 250 may be the same as the drivers side. Get some extras at the junkyard.
Power steering brackets for the 292 are rare as most were used on fleet work trucks that came with no frills.
The water pumps are different. The 292 pump has more outlets. The pulley shaft should fit, but the harmonic balancers are totally different.
When I rebuilt my engine in 1977, we just pulled the hood and swung in the engine only. When I rebuilt the original engine in 2005, we tore the dog house down and swung in the whole engine and tranny. It makes getting to all kinds of connections a lot easier, but then you have to rebuild all the body work again. [Also we installed with the wrong throw-out bearing and it had to be changed, so the driveline and bellhousing had to come off again-- Murphy's Law bit me].