Small 3 wire alternator for race cars

At Eclectic Motorworks, we're about the update a TR7 vintage race car with a lightweight modern alternator after having it go through several "Lucas" units in the past few seasons. I put "Lucas" in quotes because most of them have been brand new Lucas copies made in Turkey or somewhere. 

Many vintage racers are using compact, low output Japanese alternators. I think the common ones are 40-50 amps and designed for forklifts, tractors, etc.. They're all over eBay for pretty low prices while some of the racing suppliers sell what looks like the same thing for higher prices. We could go that route, but I thought I'd check with the hive for ideas. 

Here is the criteria:

1. 40-50 amps. More is okay but not needed. It seems like most "modern" alternators are 100+ amps.
2. Compact, lightweight (that rules out good old GM alternators)
3. V belt pulley
4. Three wire so it can light a warning light if it pitches the belt or stops working.
5. Able to be spun constantly at race RPM (let's say 7-12K RPM alternator speed) for 30 minute sessions without overheating or destroying bearings.
6. Ideally, common and readily available at auto parts stores.
7. Closer to $100 than $300.

Summit Racing sells this one:

https://www.summitracing.com/parts/tsn-es1004#overview

It seems to fit the bill except maybe for item 6. We could just buy a spare for the customer. Or is this a common alternator? We don't mind helping Summit stay in the black, but if there is another easy button someone can share, I'd appreciate it.

The Jungle Store has this one: https://www.amazon.com/DB-Electrical-AND0212-Alternator-Grasshopper/dp/B0081SB17E/

I think the Summit one you're referencing is a one-wire unit.

I would just pick your favorite flavor of early-mid 90s japanese car/truck. 

https://www.oreillyauto.com/detail/c/ultima/ultima-70-amp-alternator-remanufactured/ost0/r111405a?q=R111405A

That's from a 22r toyota truck. Looks like it's stocked at every location around me. Not crazy expensive.