Yes indeed, buy the wheel first and then go looking for the boss kit. Iif Pep's don't know what they are talking about, deal with the manufacturer/distributor directly to get more details.
The cool thing about Autotechnica boss kits is that they usually come with the PCD for both Autotechnica and Momo on the one boss kit and you just rotate it to suit your wheel. Yyou will still have a boss kit length issue though leaving the indicator stalk to close to the wheel in the low-beam position.