problem with seat and seatbelts mk1

i have a pair of coupe s seats, that have been in my mk1, i just about got the original bar type seatbelt catch,on the seats, but they wont go forard or back, same problem with the mk2 seatbelts i have that are fitted now, i weant to use the original bar type catches and the belts without the buckle on ,but there too big, and,if i use the mk2 ones out (of a ranger),the actual reel will bolt in with a longer bolt, but the securing lugs dont match-therefor the belt moves about,how have other people got round this problem when fitting mk2 seats into a mk1?