Are you thinking of the Ford Windsor 302 block (~180 to 250 hp)? That thing dates to the '60s and, as far as I know, was discontinued around 2001 or so. Some of the hot-rod folks still use it, but I think parts
might be getting hard to find.
If you're repowering, I'd look for something that's currently popular and supported. Mercruiser's 4.3 V6 (about 190-220 hp) and 5.0 V8 (about 260 hp) will be in production for the foreseeable future, are popular and relatively inexpensive, and can be found used all over the place. Volvo Penta
builds pricier engines with higher-quality parts
using these same blocks at the same power points.