Early vs Late 3v Crank Pulley Differences?

So I thought I'd share an update on what is becoming the most annoying saga...
As it turns out, I do not need a 3v pulley. My Sanden compressor bracket for the peanut compressor retrofit changes the belt layout to two belts: Crank->AC->PS and Crank->Alt->WP. My 3 groove pulley lines up correctly, the third groove just remains unused. So I can use either a 3v or 2v pulley.

According to the guy at CVF, both the pulley depth and the groove spacing are different between the earlier cars and the 70+. CVF only offers an underdrive 2v pulley (5.25") for the '69, which would be pushing it even without AC (although I do have a cold case radiator, which should help some).

I wanted to keep the 7.25" pulley diameter to overdrive my water pump, same as the factory did. I managed to find what I thought was the perfect answer - a 3v pulley from an air-conditioned 68 Satellite 318. I'd been hesitant to buy a used pulley because my primary concern is the rubber deteriorating and allowing the middle pulley to break loose and bang things up (my understanding is that it's mounted on rubber), but this pulley was all metal - apparently they did that early on.

So my pulley got here today, and to my surprise the inner (water pump) groove diameter is the standard 6.25. The other grooves are the same as my '69 3v pulley. Great... I can probably get away with it until May or so since the worst of the summer heat is over, though. The other issue is that this pulley is not steel like my '69 - it's cast iron and HEAVY. A good 4lbs heavier than my '69 when measured on the scale, over 11lbs total. I imagine it's going to be an absolute boat anchor at the end of my engine, so I'd be willing to eat the cost if I could find a lighter steel or billet 2v pulley in 6.25 diameter while I wait to see if I can get my '69 pulley rebuilt with new rubber.