JTR has been around since I think the late '80's, building and selling Z car engine conversion kits since at least the mid '90's, did my first JTR V8 Z back in '97. There is no reason to be leery of JTR. Customer service is is reliable, they stand behind what they sell. They are well established having been around for long time, they plan to continue, having invested in some very nice CNC equipment over the past couple years that is helping them to not only improve their current kits, but offer more kits and engine conversion bits and pieces for other vehicles. I keep in touch with JTR on a semi regular basis and the past few months they have been real busy, as such, delayed E-mail replies are to be expected. When time permits, JTR is good at replying to E-mails, phone calls, etc.
I do know that shipping to Canada is expensive and Mike has mentioned is also a bit of a headache, so be prepared. If you have a friend/relative on the states side of the border that JTR can ship to and then you/them can hand carry the parts across, you might look into that.