I did my first cycle my freshman year in college during pre-season lifting for football. Young, dumb and lucky, I made good gains. I commend you for coming to T-Nation to pose your question. There is a wealth of knowledge on this website.
I agree with some of the other guys. I think you have a lofty goal if you want to gain 50 lbs of muscle and move from safety to defensive end in a season.
What division is the school that recruited you? Just curious. Football is football and God love ya for playing the game.
I too would consider getting red shirted. You're only going to get stronger and stronger. The NFL is full of guys that were red shirted. As you know, being red shirted is a strategic move to get the most out of young players.
And just being nosey, why do you want to go from safety to defensive end? If I were you I'd shoot for gaining 25-30 pounds, keeping your speed and playing linebacker. Linebackers have all the fun! lol Back in my Al Bundy glory days I played nose, so I know the defensive line. I was too slow for LB and too short (6 ft, 265) for DT and DE.
Whatever you decide I wish you the best of luck. One bro to another just make sure you do your cycles the right way (unlike me in the day). I'm no cycle guru but there are a shitload of them that are on this board. Take their advice and keep us informed on your gains. We'll be your biggest (juiced) cheerleaders!