If memory serves me correct LCT makes VFC and TM designed AK parts out of steel. Might be able to get a 47/AKM style gas block rear sight block. I'm not sure about lower grip cap and barrel ring though.
Personally I'd just worry about the Front sight as there is a higher chance of the gun falling over and damaging the front sight then the rear sight block and gas tube braking. LCT parts are on the expensive side so you may just go front sight and later on gas tube and rear sight block.
http://www.lctairsoft.com/parts_list.htm
order from sites that carry LCT like WCG shop