No the front sprockets are not interchangeable between MC28 and NF5.
You can see pretty easy the difference on the pictures below.
RS250 NF5
NSR250
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Owner of : Honda NSR250 MC28 95sp colours / Honda NSR250 MC18 R6K SP / Honda RS250 NF5 89 in boxes / Honda C50 12V cub / Honda C50 12V super cub Japanese version /Yamaha XT600 89 benetton