the new ones they are selling are plated aluminum.
whoever built it probably just did a crappy job. lots of people kit their bikes, they never get them running right or seize them, so they sell them and say 'it just needs tuning' to some poor schmuck.
i'd start over, take the cases apart, check all the bearings, seals, gaskets, etc. make sure you don't have an air leak. set your timing, etc. you'll spend way more time in the long run (and maybe smear another kit) over just starting over and doing it right.
phbg is easy to work with because there is a little shorty cast manifold, and 10000 people have built it so you know exactly what tuning parts to change to make it run. i prefer a VM 20 mikuni but you're going to pay more for intake.