The 7300 kits "looked" better, do not know about power. Pistons still the weak link. When the kits are less than $50.00 a whack I understand the attraction especially for the cutoff saws. There was a batch of 6400s that again "looked" good but nobody gets excited about the 6400 or 7300 sets. The super cheapys are scary looking, no idea where they come from but they looked baaaaaaaaad.
AM Standard bore= check the bevels, check the bore and upgrade the piston. AM kits need to be less than half the price with the up graded piston for me to consider them an option as a person who would want to own the saw, unless it is truly just for kicks. Exceptions made for extinct OEMs sometimes, still would not want a BB kit with the piston/rings that usually comes with them.
Just took apart another Stihl 460 with an AM kit that shatter the piston after hanging a ring. Rings were worn before it destroyed the piston and cylinder. Rings wor unevenly and deporpotionally to the piston and cylinder. Get to split the case, way to many piston and "NiSil" fines to risk the rebuild. Supposedly a $100.00 eBay kit.
My opinion is unless it is truly for kicks, go OEM. BB kits and AM kits are in general toys not tools unless you can fit an OEM piston or at least a Meteor quality piston, even then it is better but not as good. Also not all of the AM standard bore cylinders are a good mix with better pistons. Buyer beware. They have their place just do not expect it to be anywhere near the same place as the extra money spent on the OEM.
Where you are at right now is why I no longer own any of those chainsaws. Not enough local used parts to feed my habit, no local new parts and the only good options were OEM. Nice saws though.