I currently shoot carbon mfx 500's at 29" w/ 225 up front. What aluminum arrow, length, & point weight would be a close starting point to match these? I did shoot the autumn orange alum arrows when I was young but had no idea if they were spined correctly or not and out of a compound. Would love to have a dozen or so of those to shoot now. My bow is a 56@28 r/d longbow cut 1/8 or so from center. I draw close to 28. Thanks.

Easton XX78 and XX75 are available in 2114 which is 510 spine and 2212 which is 505.  This is very close to the spine you are shooting so it should be no problem to get good arrow flight if your current set-up is working.

2016's are .500 spine

Easton 2016's are 0.531", not 0.500".
Damn their "new & improved" system.

I know, I know, it's only a difference of
about 3.7 pounds static spine, but who's counting?   :D

2016's will work!