you could post a photo of your boat on photopoint.com, then paste the url here so we can take a look. Difficult otherwise, should have a big triangle decal on the sides, at the back, I mean aft, end, does that help?
No it's not a Fletcher. Wrong shape. I'm not sure what it is, it dates from the 60s not the 70s. There were zillions of small boat builders then that have long since vanished.
The bows shape, I mean the combination of the squarish shape with corners at the foredeck level but deep vee at the waterline level, combined with the little tumblehome at the back, suggests it might be an early Simms, as both those styling features were on the Simms Super Vee range in the 70s and early 80s. Simms were a very respected make in the 70s and 80s, up there with Fletcher or even a bit better.
It also looks like it wants a short shaft outboard not a long shaft (I mean the height from keel to transon top looks like 15" not 20") - that agind suggests 1960s vintage. It will make it harder to find a secondhand outboard as nearly all outboards of the power you need to go fast will be long (20") shaft. But you could fix that by building up the top of the transom if you want.
If you really want to know the answer try Frank at Outboard and Hydroplane Services in Ormskirk Lanacashire, I bet he will know (he did much speedboating in the 60s and 70s with Team Mercury and had a dealership then in Simms, Fletcher and others, he still has the shop even now). Good luck, and let us know the outcome.