The hoses aren't the problem but the caliper mounts are, easiest option is just to swop the rear axle over and be done with it (there are a lot of excelent drum rear axles on the market but they are practically worthless). You should find that the flexible hose connection is the same as your existing one.
With regards to the front you will have to check how many circuits the replacement calipers have (could be two compaired to your one).
My 1986 ex-MOD 90 runs rear discs & vented fronts (single line system) ok using the original master cylinder, in fact the braking is spot on with very little peddle travel.