CR 250 engine problems

I've had some engine trouble with my 2001 CR 250 and I'm wondering if what I plan on doing will fix it. It had a couple Wiseco top ends done around 50 hours. Then we had to put a Vertex in because Wiseco was out of stock. The Vertex dealer messed up and sold as a too small piston (66.36) Why the heck would they make a piston smaller than OEM??? Well anyways that piston rattled apart and the skirt went to pieces. So we took it apart, removed all the pieces of piston skirt, got the cylinder measured (supposedly was good) and put a new Wiseco in it. It ran with a noticibly different sound. It ran good, but seemed to be missing a bit of power. Ran it for 2 hours. Go to race and after practise it will no start. It seemed to be kicking over way to easy so I took out the smark plug and put my finger on the hole while kicking. It didn't even have enough compression to blow off my finger. So after we take it apart we find the cylinder head has a ring of ruff, what looks like burnt on metal flakes on it. The top of the piston also has this pattern of stuff. The cylinder is all scrapped up and there are some sharp edges on the ports. So I've bought a new cylinder, head, piston(Wiseco 66.40), rings and I'm wondering if this will fix it. The connecting rod has no visible damage and has no up and down play, but it does have some side to side. Is this bad? Also when you put a finger on the flywheel and spin it, it has small up and downs, it's not perfectly round. Is this normal? Does it matter? So does the bottom end need doing or should this fix it? Any ideas what went wrong the last time?
We run 50:1 Bel Ray MC-1
380 main and air screw are only jetting changes
Thanks