I'd wait for the guys that regularly do this, like Dougie and Richard Mayor, before giving up hope. My best guess is you'll be looking at triple 2" SUs, raised compression, some head work and exhaust headers. It would be best to find someone who has done the modifications you're considering and using it in the way you plan on using it. 200 hp in a motor used just on track will be fairly "mild", but the same motor used on the street might suffer from cooling problems on a warm day in traffic. One of the difficulties with "hot rodding" a Healey motor is it's not just a matter of bolting on parts, like an American V8. There are lots of bolt on cylinder heads, intakes and headers, along with cam choices for someone to make a good estimate of the power a V8 will put out. With a Healey, there aren't a lot of choices for modified cylinder heads that will bolt on and finding an engine shop that can modify your existing head is going to be kind of difficult. If you're working on a budget and planning on a rebuild anyway, it might be easiest to approach this from the standpoint of "which modifications can I do that will give me the most power, ensure street driveability, and cost no more than a certain amount of money" and then determine if that will satisfy you.