I agree, the 145gn ELD-X and/or the 150gn Accu Bond Long Range are about all the "heavies" you're gonna get to stabilize with your standard .270Win 1-10 twist barrels. Or maybe I should say: "the 150gn class of cup/core bullets". With the normal 22" barrel, you may get 2950fps with the 150's. Have no real world experience with the .270Win + 150gn projectiles. Like you, I've mostly shot the 130gn and "back in the day" they served me well as a 0-400yd bullet while using hounds for deer hunting here in N.C.. That's was probably 30 years ago and about the time I really starting stretching it on out there and pursuing long range hunting encounters.
If you decide to re-barrel the ole' girl definitely get a 8t and it will make a world of difference in the artillery you can serve up.
All it's going to take is one new, great .270 cartridge, marketed right, and the .270 cal will be in the spotlight. I like 6.5's and 7mm's but look what's setting right in the middle of those two great, long range calibers!