Hmm, I have a 72' engine that has been ported, but given your info (and thank you)I guess the other engine must be later and that's the one that came out of the frame (I bought a piece of crap because it had a good running stock engine in it which I was going to put into a sidecar outfit). I don't think it's a 76', though. Maybe I should look for a 76' frame and just lighten it, put a CDI in the 72' engine with big carbs on it, and go from there (?)
Because the 72 uses points it actually has the 73 and up right side engine and oil pump cover (At least the pics of I have of 72 h1's do). I am pretty sure you could get a 73-76 cdi setup and adapt it to the engine. You must get the whole cdi setup however and you cannot mix and match 73 cdi parts with any other h1 (73 was the only year the h1 used the h2's cdi unit, it won't interchange with any other h1 parts).
The Frame numbers should seill be stamped on your frame even if the headstock sticker is missing. The engine numbers are hit or miss, they are rarely ever within the frame number but if they are within a couple of hundred then you might have the original motor. Rick Brett the triple expert would be able to tell you more about this. As for the engine frame numbers, here is the kawasaki triples reference site (complete with free downloadable kawasaki service manuals!):
and the page for serial numbers:
and here is a page were you can get a good look at all the h1 models:
The easiest way to tell a later H1 frame is at the very end of the top frame rails there will be a mount for the tail section (this mount will also be there on h2 frames). The earlier frames the grab rail fit into the back of the open tubes like this::
The tank mounts are also different. The 72 and earlier tanks have a tab and bolt on below the tank (the tabs are below the top rails as you can see above just ahead of the reflector), the later tanks are slip fit like a honda.
As for the frame the lighest cody (that is his cafe racer in the earlier post) has been able to get is I think about 325 in street trim and he has done everything (even anodized excel aluminum rims). If you want to go even lighter you can modify an fzr400 to take the h1/h2 engine (the rear wheel is pretty close to the chain line on an h1 spot on for an h2) since that bike is pretty much all aluminum (only the subframe and lower rails are not).
John Aylor (JA Moo on the kawasaki board) has a 75 frame that was already braced for racing (with title) for sale if you are willing to pay the post from new mexico.
If you feel like spending big dosh, there is a firm in england reproducing the H1R/H2R frames but they are a couple of grand.
I alightened 76 frame might be the way to go, espically since you could probably get one for a lot cheaper than it would cost to modify something else.