My local Nissan dealership(Midland Nissan Perth) supplied my head gasket,all chain guides and sump gasket etc.Bearings are availible through repco,veale parts shops in either acl or ntc brands.Take your timing chain into your local trev speed shop to match one up(mine was made in germany)and shortened to fit.about $80.
If your head is ok,mine cost about $2200 with arias pistons,all machining/oringing,balancing etc.You save the money by making many phone calls and doining the labour yourself.
Good luck
Todd