When there were head to head match-ups Trump would always lose & the best poll was him squeezing ahead by 1-2% at best when Clinton would have scam while Kasich would be ahead by 6-7% & same with Rubio.
If Kasich is at the top of the ticket (with Rubio), then NC, CO, OH & FL (with Iowa) is going to GOP & surely they are winning the White House. Additionally PA, MI, VI, NH could go GOP.
I think Kasich will cross the 300 mark safely with a 4-5% win, the map would be similar to what Obama vs Romney or McCain was with a little change here & there.
Both Kasich & Rubio will do incredibly strong among non-white, Clinton's strongest group & could crack Bush's 40% Hispanic vote odd. Look at what Rubio is doing now in Florida Senate race among non-whites vs other GOP guys. Kasich is also doing strong in his state.
In the end Clinton has too much baggage & corruption & that would catch up to her despite the attacks agaisnt Kasich. He is a moderate face, people would not be forced to vote for Clinton to keep Trump out. I mean that is what Clinton's whole campaign all about!