That weeds out DOHC engine, no kickstarter on them at all.
You will tear out the kickstarter gear there, it is geared backwards for leverage and will tear up quickly. As well, it is not positively driven both ways, one way it slips 100% and that engine will not be hooked up to the other.
When you join any engines you join at the crank pretty much only, if you use primary drive you will tear it out too (as someone else pointed out and he is an expert on SOHC) as it breaks too with only one engine on it not two.