Valve jobs are all dependant on the port. Some ports need a radiused valve job (bottom cut is a radius), some don't. Matter of fact, I spent $40 on a certain Newen cutter reccomended by someone very respected in the TM porting biz, and it indeed picked up flow, but only on the intakes. On the exhausts... it LOST flow, and that's where a radius cutter is *supposed* to excel at. (this was on a ported G head) So, the exhausts ended up getting a conventional 3 angle that I cna't reveal the exact angles
BTW: the thinnest the 45 is, the better the flow.... but at the expense of poor heat transfer which breaks down the seat/valve sealing. Also... there are 50 degree seats and more... (on the Hendricks SB2 heads we got it had some really funky angles) Those flow even better, but the valve takes a beating as it's trying to drive past the seat vs sealing.