I took a FWD 164S engine, put it into my RWD Milano/75, THEN bought a Alfa SZ crank pulley from England in 1997.
I've mixed and matched off-the-shelf-parts (how unscientific of me!) Been using it ever since .
My latest project is that 24v Milano that I bought from AlfaRacer75. That car DOES have a vibration issue but I haven't determined if it's from the engine or from the driveshaft.
I meant that I would be the first to get bad engine vibration from mixing and matching. I think yours always worked out.
Jes
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87 Milano Verde - daily driver - Juliet
87 Milano 3.0 Motronic - budget race car - Roxanne
87 Milano 3.7 24v - race car
(Repeating what I suggest or do is at your own risk - be critical)
Notice that there is no rubber component to these. e.g. NOT harmonic balancers - They are just pulleys. Perhaps they are not balanced to the engine at all, but simply balanced (like you would a wheel).