@ $ 1k, you'll pay the duty but you won't know (exactly) what it is until customs tells you and won't release the shipment until you do. you'll get a notification in the mail with info and instructions.
but if you need all the kit parts, that's your only option than pay the guy who already did what you're doing.
you can get good deals on the engines online if you ask "hey can I get a break on 5?" then just buy bulk kit parts from China. $65 per 66cc engine alone off fleabay. seen $62 once, sold out fast. im watching a guy sells 48cc's for only $59.
you can get the individual parts of kit for pennies on Alibaba. 3 weeks to get em.
make a list what need to install. then buy 10 this. 10 that, etc. no tariff bcs your total order is like $350, shipped. I see these deals on Alibaba, 20sets grips $19. 44T sprockets $2 each moq 20.
China loves to move their stuff. they make too many of everything lol