IIRC EMPI had their own length lug between the OEM steel & alloy sizes for those wheels to get full thread depth engagement.
There are several new repops/repros of that 8-spoke style out there who may also sell that length & type lug as the original EMPIs. Look in Hemmings Sports & Exotics for their ads, or in the Classic Motorsports 2014-15 issue which covered all the new & repro period wheels now available - including at least 2 repops of your style. (sorry, but I don't recall which issue, but the article should be up on their website by now).
Cheers, Happy & Safe NY!
Tom
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