swap rewiring

I had a blown 22hp briggs 407577 on my poulan pro PD22PH48STA rider and found a good 18hp intek briggs 42A707-1238-01 that I replaced it with. My problem is the wiring harness is totally different and I need some advice as how to hook it up so everything will work as it should. The new engine appears to have no regulator but the old one did..it was a 16 amp DC at 3600 rpm regulator and 28 volts AC alternator. I had some advice on a push button starter and toggle switch kill but would rather use the key switch. Starter is hooked and it will run with key and I cut and connected black wire so it shuts off but the charging system has me asking for further advice.