What would differ in an engine rebuild with a small boosted setup (i.e. basic snort kit running low boost) or basic NA performance in mind?
Is bottom end strength not such a great consideration for NA? Do you use different type of pistons depending on which?
Things like port and polishing the head would be benificial for both would they?
Cam shaft selection would be application dependent?
And I guess compression ratio is different depending, but do places like JMM and IT'S Performance and that change the standard compression much in there rebuilds?

generally for big boost you want lower compression ratio, and for a cammed NA you want higher. If your only looking at low boost or a mild NA setup leaving the CR stock will suit both.

Cams are different. Mild cams can work for boost, but the big NA ones wont.

other than that, both benefit from the other stuff like good bearings and rings, balacing the bottom end, head porting etc.

Ring gaps and big end clearances are slightly wider.. Due to heat and expansion.. Bigger clearance on big ends and high flow pump to make up for turbo oil feed and extra flow through bearings helps no end...Thats why quite often an negine with an easy 120.000 klrs or so makes a good turbo engine... It's clearances are about right..Piston clearance is alttle more also...Depending on brand and type...