It's normal for small frames to be oversquare (i,e, top tubes longer than the seat tube) but that does seem to be a bit stretched. Unfortunately, Miele did not publish their geometry measurements. However, it was a sports model, so the angles will be relatively slack.

The Binova should use an English threaded bottom bracket. A traditional ball and cup bottom bracket will start at about $10-$12 CDN. A more modern, maintenance free, cartridge bottom bracket will start at about $15.00 CDN, though it will require dedicated tools. Of course, the prices go up from there, depending on the level.

27.2mm is a common seat post size for a typical butted tubeset, with a single butted seat tube. Plain gauge CrMo (4130) typically run from 26.2mm - 26.8mm.

BTW, I suspect your Binova is closer to mid-1980s, circa 1985-1986. I'd appreciate a good , drive pic and the serial number.