Looking for Experienced Opinion.

So My first Bike as an Adult was a 78 CB-750. I learned how to Rebuild an Engine with it, and I've really spent a lot of Time with it over the last 4 Years and I kinda wanna do something Fun with it now. So I'm Thinking about making it into kind of a Drag Bike Replaca for the Street. And maybe ill take it down the Track a Time or 2 idk yet. Im not really interested in forced induction, thinking more of a High Compression Big Cam Build. What I'm Wondering is how far can I go before I need to start worrying about the Transmission? And should I be Thinking about After Market Carbs, or can I get pretty solid Performance from the Stock Pumpers? Here's some of the Stuff I'm currently looking at.. The Piston Kit is a 67.5mm Bore (900cc), and will increase Compression to 10.25:1.. Any and all Opinions appreciated. Thanks ...

I would suggest buying a used CB900 and converting that one. I'm no expert in oversized pistons, but going to a 900cc makes me think that air-cooled bike wouldn't do well as a daily rider in traffic. But I could be wrong.
As for carbs, I've heard great things about flat slide carbs really giving life to the bike because the throttle response is so crisp.

A dead reliable big bore with no concerns would be an 836 but the one you are looking at is also good. Anything from cycle x is going to be good product. I use them extensively. Is you bike a K or F? Either way you will need to do better connecting rods, heavy duty cylinder studs, heavy duty cam chain and primary chains, I would suggest looking at upgrading timing chain and primary chain tensioners, have the crank balanced, upgrade to undercut transmission, to make it run good you need to have the cylinder head ported and larger valves installed....this is where all the power is in the 750, you will also need new rocker arms with the new cam.

Stock carbs will run but the aftermarket carbs are much nicer and easier to tune. I have run stock carbs on 970cc no problem

I have done big bore builds and hot street and drag builds so feel free to ask questions and look at some of my pictures. Ken at cycle x would 100% set you up and give honest opinions on what to use.

You will find out very quick that these engines are very expensive to build correctly, I have around $7000 in my drag bike engine and easily have $4000 into my "street"970cc motor. When you start pushing more power than stock you have to upgrade a lot of stuff to make it live.

K I believe, Not 100% sure though. It was Advertised as a 78 When I Bought it. It has 78 Tank and Carbs, but the Title Says 74. I Assume a mistake was made at the BMV but with a 50 yr old Bike who knows what exactly happened. And I did Plan on having the Head Machined, fortunately for Me I have Family Members that have spent Their entire Lives in that Field so I can Save a little there. But Yeah I don't Plan on being Finished by next Year or even the Year after.. I definitely plan on Riding it for more than 10 Seconds at a Time so I want things done Right even if it takes 3 or 4 Years. Plus I have other Toys so the wait won't be too bad.

If the frame has the VIN stamp, that should tell you what need to know. If it doesn't, the DMV likely took the previous owner's word for it.

I have fun with my 78' K model. 836cc flat top pistons with a mild CX-1 cam, 79' CB750 swingarm (about 1-1/2" longer), 16/54/530 sprockets, and spacers in the bottom of the forks to drop the front about an inch and a half puts me in the high 12's/low 13's right at 100mph.

post the engine serial number and can tell you what it is, will help to determine what parts you need. F pistons and K pistons are different so you will need to know what you have to order parts anyway.

Is it possible the PO put different carbs and tank on a 74? And if so, is it possible there is a later year engine in a 74 frame?
I'm assuming the DMV is correct and then the bike had different parts put on it.