I forgot to update but I bought a 415 bicycle chain tool on amazon for $15 and cut the chain. The chain came with a clip link so that's what I used. Rode the bike around and did my first track day session on the chain. Definitely need to keep an eye on the stretch and wear along the chain. I will probably go back to a 520 chain when I need to change the chain. Its more peace of mind and less worrying about "Did I check the chain slack? or did I lube the chain?". Plus I just started doing track days and plan to go race only so until I get fast enough to qualify for MA junior cup
I don't think I need to worry too much about the reciprocating mass difference between chains.