[ByronRACE]

The boss block is heaps stronger than the production 289/302 block, and for that reason alone is desirable.

That said, if your build is not going to exceed 400rwhp, there is no reason to suffer the expense of the more expensive build. A factory 289/302 block of any year will handle 400rwhp without failure; I've tuned many hundreds of them.

As far as the SB100 issue; it's only an issue if you intend to exceed 400rwhp or so and have a real need for the strength of the boss block. If you go to the CARB and register the car by engine year, they will look at the engine ID and most of these guys know what a vintage small block Ford block looks like, and where to find the numbers in the casting. So, I'd suspect there's a strong possibility a boss block would not pass scrutiny.

By the way, unless you are going to spin it above 7500rpm, build it 14:1 compression, or install a power adder, you're not going to exceed 400rwhp so that might help you decide your path. 400rwhp is around 460-470 at the flywheel.

Byron