If you have the 180 generator then all you need is a better stylus/cantilever designed for this generator.
I do not have my old AT-ML150 on hands now, but i have AT-ML170 and AT-ML180 - my top cartridges, i just love them, they do everything right compared to many other serious cartridges of much higher price. Last night i played records with AT-ML180 on Victor UA-7045 tonearm against FR-7f on Lustre GST-801 tonearm with Luxman silver SUT. I have not used AT-ML180 for a while, but the sound of than Audio-Technica is just spectacular! I can not say the same about AT-ML150, it was good, but not so impressive. Cartridges are impressive of not, but it's important to make comparison. Two days ago i just put together my new stands for 2 Luxman PD-444 aroung a rack with different phono stages, sut, headamp. Now i can use 4 tonearms, must be some fun for the winter.