Thomas,
Think of it this way, your .600's w/250 gr, points @ 512 gr. weigh more than my 30" .500's w/standard aluminum inserts and 175gr. points.  Fine for most things that won't try to eat you!
Fans of UEFOC are finding out that one way to get there is modify/double insert a shft that would normally be weak for their set-up, but effectively stiffening that last several inches of shaft and allowing additional tip weight that would not normally be possible without it.  Your footings are probably the only thing that let you get away with 250 gr. and still fly well.

Personally, I never liked the idea of adding weight to the nock end, point weighting is always preferred, its why back in the old days they footed shafts with a denser, heavier hardwood. Tie a string to a rock, and throw it, which gets there first , the string, or the rock ? Id just as soon the rock (point) does.

I killed two hogs this year with a 45 lb longbow and 15/35`s. I had a 100 grain insert and 175 grain point. . Worked fine. RC

I believe the Carbon Express 90's weigh more than the Gold Tip 3555's if I'm not mistaken. So is there any reason that wouldn't be a good solution?

Right now I'm shooting       grains efc 28%  out of my bear's paw classic 45@28 at my 27 draw length  seems to be very forgiving and accurate     w good penetration on my target    

I would say Bill and Tracy answered the question pretty well.

For my 47lb Palmer I have to use a 125gr head for them to fly perfect. The arrows comes to around 380 grains which is ok for 3D but to light for hunting for me. I use a CE 150 with 200gr broadhead which comes in at 521 grs.