Hi John,
if you Google flag pole manufacturers and look at their hurricane rated poles these will serve well as a mast. Most of the manufacturers are in the east and south of the USA so transport is the big cost. There are also manufacturers in China that can be accessed through Alibaba, they will build a custom section to your specs and their prices are very competitive, however transport effectively doubles the cost here in New Zealand, it may be less in Canada, possibly worth a bit of investigation.
My previous boat, Arcadian, had fiberglass masts that were not tapered and these performed well although they did not look as elegant as tapered masts. The layup thickness reduced from about an inch at the partners to about a quarter of an inch at the top, so there was a slight amount of taper on a ten inch internal diameter mast. The mast I have built for my present boat, Gypsy Rose, is a six inch diameter aluminium section with a tapered solid wood topmast. This was relatively easy to make and looks reasonably elegant, so is, I think, a good compromise.
All the best, David.