B23 with B21 K-Jet system

[jaluhn]

Has anyone had any experience running a B23 engine with a k-jet system off a B21? The reason I ask is because we (the shop I work for) have a customer that brought in a early 80's 240 with a B21F that he wanted rebuilt. However, we have not been able to get pistons for the B21, and one option we were considering was to use a B23 bottom with the B21 head and externals. B23 pistons are apparently much easier to find, and the blocks are externally identical, so assuming a B23 head gasket will work will a B21 head we think it will physically work. My concern though is with the fuel system, specifically the fact the the displacement will now be ~10% greater, and consequently the air flow. I know the K-jet system is very precisely calibrated for certain airflow and fuel flow ratios, and as an engineer, it seems to me that changing the air flow could cause problems, most likely leaning out on the top end. But, the change is small enough it may not be that much of a problem. Hence the reason I ask for experiences.

Also, if anyone had / knows of a set of B21F pistons, specifically for a 81 or 82 (not sure if there's any difference between early and later B21 pistons) and preferably 0.040" over, please let me know. We have already tried all the suppliers we know of (including RPR & IPD) with no luck, as well as the engine part supplier out machine shop uses.
Thanks ~ John