...almost any sealed unit bottom bracket assembly of reasonable quality will do pretty well, and should accommodate your needs for training miles and the race itself. The best ones are stuff like the Phil Wood ones, which are pricey. White industries has offered some in the past, but I don't know their current production. But almost all of the better Shimano units (not the cheapest ones, but a UN 55 or better), usually last quite a while. There are many others that have been made and sold over the years. I have a whole box of used ones in various spindle lengths and cup configurations, that I use on projects. Ofmega, Campy, Stronglight, Galli, Mavic and some others I can't remember right now all had some high quality BB's they made and sold over the years. But I'm guessing nobody cares if your race bike has a bottom bracket unit that is newer than 1989, so cut yourself a break, and just buy something off e-bay or Amazon that has the right spindle length and tapered ends to fit the crank you use...even if you buy new.

The optimal spindle length for any crank has usually been defined by the manufacturer at some point. So I usually just look it up over on VeloBase, when it's working. It also has a section on bottom brackets, but for your purposes here, it's probably more confusing to look there and try to work backwards to the crank you end up using.

I've never been a big fan of Biopace rings, as I find they don't seem to fit well with my pedaling style and cadence. But I do use them in the smallest sizes as the smallest chainring on a touring triple. I don't ride a whole lot on gravel, even though we have a lot of gravel levee top roads here, so if they work well for you, I'm sure they're out there. The co-op here has a whole box of Biopace rings that nobody ever seems to use.