can you have the working old shower head cleaned or refinished to improve the appearance?......Google "cleaning pitted brass taps" eg sugar and lemon juice or tomato sauce !! failing an improvement form cleaning consider refinishing the surface: check metal polishing, electroplating, anodizing, enameling or powder coating

Removing the flow restrictor wont help, as the knuckles in the modern shower head set-ups are too small and wont allow sufficient volume of GF hot water through. Best detach the old rose head from the pipe/knuckle set-up, throw it away and then find a rose head that you can adapt to the old knuckle /pipe set-up. It's what I did when I reno'd my bathroom and every thing works fine - good flow with good temp. Plus, you can also buy pressure equalising washers for the cold tap which will give you even more control balancing the hot and cold water.

Thanks Peter. We did end up finding a new shower head that fitted and it’s adequate for now. The HWS will be replaced in time. Appreciate your comment😊