Please school me on the 87?? hybrid pulley system

[HeavyD]

So I went to look at a 350 engine block, and the guy pulls out a set of pulleys from an 87ish tbi truck that had the ribbed area for the alt and the classic Vbelt for the ps.

He wants $150 and said these are "rare, unavailable repro in steel, and "a must have" since they won't squeal yet don't cover the engine like a serp system does.

Quick google search shows that 6 rib systems from March etc are aluminum, usually underdriven, and while great looking are definitely not steel stock replacements...even rock auto doesn't show anything.

So after this babbling I am asking:

1. Are they actually hard to find??

2. Does this setup with ribbed belt work a lot better than a vbelt? Goodbye squeal? Alt squeal more than ps usually?

I always liked the vbelt unobtrusiveness but hate the noise...this hybrid thing is new to me.

Thanks.