Hey chewy, welcome to the addiction lol and the forum too
The engine kit appears to be the typical 2 stroke one offered by any of the dealers who's ads flank both sides of this page, they're usually about $150 for a complete kit. I'd recommend a vendor known for excellent customer service & participation here on the forum in case you run into any problems. While tire choices are nearly infinite (I'd actually recommend checkin' out yer local bike shop for 'em), triple tree forks are slightly more difficult to find - lookin' at that pic, I almost wonder if the builder modified a regular set to get the look... but I dunno for sure - I do know that someone w/a set will prolly chime in with a suggestion. The exhaust/expansion chamber looks custom - but something similar can be found here: SCSW tuned pipes
and even the Sick Bike Parts
pipe can be mounted in that configuration.
Other than that - it's a straightforward build and despite your claim of inexperience these bikes are really pretty simple, you shouldn't have any problems and even if you do - we're here to help ya