68elan:
Both Ken at Dave Bean and Ray at RD are very good with shipping to Canada. Phone Bean's for your first order of their catalog and they will set up an account number with preferred shipping instructions attached to your account. The catalog is very good, and well worth the $15 or so. Ray has a very good on-line order form in his excellent on-line parts listing section on the web site. He will email back with complete price and availability, with options on parts that have variants to your preference.
A third US supplier that gets mentioned less in these threads is JAE. I believe Jeff posts here as well. i have not ordered to Canada from them yet, but understand they are very good as well.
http://www.jaeparts.com/For all US suppliers, have them write on outside of package on the invoice envelope "vintage auto parts, over 25 years old", and you will only be charged GST, no duty. Also consider shipment by US Postal Service on the smaller stuff as the brokerage fees are way less than UPS, Fedex, Purolator, etc. which are the suppliers prefered method of shipment.
For the gas tank, check out Axminster Panels on the vendor page on this site. He makes aluminum replacements that are very good. Other option is a rad shop service job on the tank where they clean and internally coat it. Local guy here wanted $300 for this job. Decided not worth it as tank may have lots of pin holes that don't seal correctly. Used tank may be available, but figured shipping would be impossible due to fuel smell issues.
Welcome to the list
Also check out Ken Mason in Orangeville for used parts; he has a few cars around although not sure if he is parting any.
http://www.kmrestorations.com/