what harmonic balancer should I get for my 340?

The balancer on my 340 is the original from 1971 and the rubber is looking old, so it was suggested I change it

Now this is just a street 340, not building it as a race motor, but want it to be respectable

Looking at a few different sites but Mancini has the most shown for my motor

on the high end of it is a Fluidamper $402.95

and on the low end one by PRO/RACE pro/street not SFI certified, but sounds like a good stock street replacement about $106.00

So would it be worth the extra $300 for the fluidamper for the benefits?

Is there one better than prorace, should I go ahead and get one SFI cert.?

MP has 2 different ones for internal balanced engines

another one that I looked at showed for forged cranks only, but also said for all internal balanced engines

right now my pully bolts on with 6 bolts and some look to have only 3 bolt holes, Does this matter?

This is so confusing

Thanks in advance