i agree with Peter, WRT the '181 you can certainly find them in small qualities in the after market, I may have a handful of them myself. One thing you are missing is a small barrel shifter, which the '181 does not support, but for a 8 bit shift it should not be terrible. Vaxen and such built their independently, but it is worth while IMO, as it allows in a single clock tick to perform pretty substantial arithmetic, although because it's a sq law the cost in die area is huge. If you look at the 68K for instance, the big area in the middle everyone sees in the pictures is the shifter (same for the Alpha chips).
Clem