You can get some cool looking flo wave indicators on ebay for about 30 quid but check your original connections cos you might need an adaptor which is about a fiver 👍
Beware ebay lighting. If your Z650 is the old Z650 you're okay. If it's the new version it needs to have indicators complying to EC Directive* 76/759, 93/92, Chapter 2 of 97/24 or to ECE Regulation 6 or 50 which most Chinese junk does not. Such a lamp will have a E number on the lens to denote compliance, typically E1. Whether your bike passes its MOT with indicators that do not comply depends on the knowledge of the MOT tester. Early 1980's bikes have no such legal requirement for indicators so the tiny bullet type would pass an MOT.