I'll try to ask this without rambling,so here goes. I'm shooting full length Easton 340 Traditional Only Arrows with a 125gr. tip. They only offer a 300 that is stiffer spine. Mines 10 gpi and the 300 is 10.1. I want to shoot heavier tips. Is there that much difference between the two to go up very much in tip weight? I guess I don't fully understand the correlation between gpi and spine,but I know there are guys on here shooting heavier bows than mine and using heavy tips. My bow is 55 at my draw length and shoots great with the above set up. My question is with a full length arrow and about 175  gr tip what arrow would you go with?

There are many people on here that know WAY more than I do about this subject.  Are you shooting full length so you don't have deal with cutting the arrows and tuning that way.  If you shorten an arrow you loose some weight, but by stiffening it due to being shorter you can gain more in tip weight than you lose in shaft weight.

No I'm pulling back and leaving an inch or so up front for the broadhead. My draw is about 30.5

The arrows you have and 175gr. tips should fly fine.