When I've setup my C band dishes here, I've always had to use 83W as the closest sat to my true south point that is usable, 78W never seems to do it on my initial setups. True south here is 180 degrees and 83 W is 196, so it's quite a way off, but that's what I've had to do here.
You're pretty close to me, I'm at 72W, 42 N, so maybe 83W might be a better choice for your first sat to try and lock onto, or even to roughly align on, maybe.
It sounds like your first dish was like one I have here, a 9' RS dish with a HH mount, which was much easier for me to setup than my 12' Conifer. It has a hand crank you can use for azimuth adjustments prior to installing the motor and the other adjustments for el and such are within easy reach, although the declination adjust on that dish is a PITA if you don't have it right initially. Very nice dish though.
You'll get it!