Liza ~  That sounds fine, and no, you will NOT gain weight eating that many calories on a ride of that length because you burned many more!  If you're really concerned/interested, you might want to invest in a Polar Heart Rate Monitor, which can estimate your calories burned during your rides (based on your height, weight, and intensity as measured by your heart rate).  I'm small (~105 lbs) so don't burn nearly as much as a larger person, but on a ride of that length (~5 hours), I would typically burn about 2000 calories!  And my husband would burn more like 3000.  So as you can see, a ride day like that is not your normal day at all, and your caloric intake can definitely be adjusted accordingly!  You could actually eat quite a bit more and not have to worry about gaining weight on day like that, but if you were okay on that amount of fuel and didn't bonk, then you know your body best.  I would need to eat more like 1000 calories for a ride like that.
Congratulations on your longest ride ever.  It's a rare athlete who can increase by 50 miles in one chunk without suffering mightily, so consider yourself rather elite!   
 
Emily
				
			 
			
		 
			
				
			
			
				Emily
2011 Jamis Dakar XC "Toto" - Selle Italia Ldy Gel Flow
2007 Trek Pilot 5.0 WSD "Gloria" - Selle Italia Diva Gel Flow
2004 Bike Friday Petite Pocket Crusoe - Selle Italia Diva Gel Flow