The PO of my L36 top swap setup used a HVIII for a L26 in the L36 UIM. It's does just need to be trimmed. You will be fine.well got some good bad and good news, I cant upgrade to an L26 UIM, unless I find a L67 throttle body to go with it, and I'll need an adapter plate, gets expensive.....
Good news is Overkill told me he is Pretty sure the Series III version will work in my car, might just fit a touch loose inside the UIM. Series II HV3s need trimming to work in a Series III.
After lots of reading, looks like the hv3 should fit fine, if i had a series III motor and bought series II hv3 then trimming would be required.I'd return it, but that's just me. That way you don't have to worry about anything.