This brings back memories of building up a 3 rib 4AG with a small port head that I put in a Lotus Seven replica. I ended up running 40 DCOE's, 290ish duration cams, and a Megajolt ignition. It was great above 4500 rpm, but was a little flat below that. I think at the time guys were using, I think, Yaris cam followers as they were the same as what you're using, various thickness without shims.