Shouldn't be a problem to build a 273 if you have the desire, basically gonna take similar parts to do the job, except valve size, your gonna have to keep it around 1.78-1.92 which means your gonna have to work with one of the factory heads, and building decent cr is a bit of problem with smaller engines but besides that 350 hp should be relatively easy with 360/5.9 heads and 400 hp be a bit more work, some porting probably gonna be needed. Other than that should be pretty straight forward.
If you look at the 473 hp 292 it basically was built similar parts that someone would of built with a larger displacement at that time, mainly ported EQ's.
If you have the desire it should be more than possible, but for most it would make more sense to build a 11's 340.