Yes you can bore out 916bip cases & can't see why you can't bore 748 cases as I believe they are the same. (later cases may be different).
I don't have any 1st hand knowledge of the 955 but have heard claims of 140 odd bhp. This would involve serious cost & you could probably buy a complete 996sps for less than cost of parts & labour.
Ferracci do a 955 kit inc crank & rods (
www.ferracci.com)