Level Carb?

15 degrees give or take is usually OK, but you are correct, the fuel system is all gravity feed and with that much of an angle your bowl can't stay full and the float can tend to stick.

Yes you can mod the intake, and yes there are 3rd party ones, sorry I don't have a reference link for you, but do you have a pic of your motor mounting so we know why had it had to sit at such an extreme angle?

At least for me I find just keeping the motor as level as possible to be the best.

That amount of carb tilt is most likely excessive - tho if it's not puking fuel or starving at wide open throttle/max RPM then there's little reason to mess w/it beyond aesthetics, the float height & range of travel would be the only real issues w/carb angle, other than what I mentioned above there'd be no other effect.

Ofc - if you've access to welding equipment it'd be sweet to make/modify a manifold that not only had the proper angle - but was shorter than the extended CNS intake as well as manifold length (and number of bends) does have a pronounced effect on performance...

I've been meaning to make one from scratch, but it's mebbe tru I've procrastinated on that lil project lol - I just took a stock kit (short) manifold & cut a slot in it, bent it a bit more & rewelded it (same method they use), then cleaned the over penetration (weld) on the inside to promote flow... it's worked well enough it's yet another thing I've not "finalized"

Your manifold looks oddly long, Is it stock? Here is a link to dax's site with a pic of one. Is a lot shorter. ENGINE_KIT_PARTS_PAGE_2 Dunno, if your not having problems, would not rush to worry about it but know what you mean about wanting it right an' tight. Pic is down the page some.

Forgot to put this in. There are a ton of options you can use. carb manifold - Google Search

You had said you didn't want to rotate the engine but is still an option for you rater then fabricating a new manifold. It gets easier, lol

My carb is at a stupid angle. Runs like a champ.