Who makes the...
 

...heaviest and straightest internal component carbon arrow, and what's it weigh per inch?

RE: Who makes the...
 

Carbon Express 'Terminator Hunter Selects' 6075's are 12 grs / inch , and have a straightness of +/- .003".

Not sure if they are THE heaviest or straightest, but they're a darn good start.
I'm shooting these shafts on one of my set-ups right now, and a 28.5" shaft w/ 3" vanes and 100gr tip comes out to a tad over 470grs.
Throw in a nock bushing , longer vanes, some cresting wraps or a heavier tip and you're over 500grs in a hurry.

I personally am starting to lean toward the "Mid-weight" hunting arrow......450 +/-. Good speed, low noise level, good trajectory.