reguarding pistons

guys,
as many of you know, i am rebuilding the engine in my 1977 240D. i thought i had all the info, and all the advice i could possibly need in order to do this. i think i was wrong. today i recieved an email from a man with whom i have been coresponding about parts. he told me to NEVER, EVER rebore the sleeves in my engine and replace the pistons with oversized ones - which just so happenes to be what i had planned on doing - because the sleeves will crack. he said that i should resleeve the engine and use new regular sized pistons - much more costly. i do not know that this man has ever done a rebuild on one of these engines. i have heard good and bad about both ways of doing this. it seems more logical to me though to get new 1st o/s pistons, get the existing sleeves bored (a mere .25mm increase) rather than to use the old 240k+ mileage pistons, or to pay an additional $500+ for new std pistons. i need to know exactly what to do in this situation! please help guys! i would love to use new o/s pistons and my old, rebored sleeves, therefore cutting the cost of installing new sleeves. if anyone out there has ever done a rebuild the way i would like to do it succesfully, please let me know. thanks guys,
william gum