well, in my experience with th older O.S engines is that their sleeves are not constructed of ABC.
So the engine will loose compressioon after some time.
Also, doing the porting yourself, well, unless you are experienced, i suggest that you don't do it, If you screw up, then it wont be too good
If you want performance without having to port the sleeve , then maybe get a new sleeve, i think Trinity has ABC sleeves for the o.s cv? Im not quite sure though, u can go check it out.
with the better sleeve and the higher compression, ur engine will definitely run better and also lasts longer than porting the sleeve u haf now
hope this helps