Honda-SOHC

Hello everybody. My first time on this excellent forum. Currently in the final throes of putting my 400/4 F2 back together. It hadn't run since 1992 and was in some state when I got it last year. The exhaust manifolds and silencer went in the bin so my question is what do you recommend in terms of a replacement system.
DS does not have any in stock yet. There are stainless systems available.
Is it possible to pick up good used systems?
Your collective thoughts would be much appreciated.