One thing to keep in mind is that 1450 innings is a ton of innings to fill. You'll probably have three closers, so that might be worth somewhere in the 200 innings total range. That leaves 1250 for starters/MRs MRs are probably good for 60-70 apeice, assuming no injury. You'll need at least 7-8 starters to fill the rest of those innings (assuming you don't play your 5th, 6th, 7th starter every day). Another option you could take is you could choose to come in under that limit, and dominate ERA, WHIP instead, while focusing more on offense. I'm not really sure what to tell you to do here. It depends on # of roster spots and a lot on what you're opponents do. Knowing nothing about you're league's settings, I'd be inclined to tell you to not do it, and to at least start by trying some high-upside starters. Later on in the season, when you have an idea of where you're standing in certain categories and what your opponents are doing, you could try the MR thing.
Assuming 22 roster spots and a 12-team league (I think this is Yahoo default), and 9 starting hitters, this leaves you with 13 spots to use on bench/pitchers. In roto, you probably want to leave one spot for bench hitting to replace guys not playing on Mondays and Thursdays, and as some sort of depth in case of injury. This puts you at 12 pitchers.
From 12 pitchers you have three closers (if you want to come in the middle of the pack in saves). That puts you at 9 pitchers. Now if you carry 3 MRs, that puts you at 6 pitchers to fill about 1050 innings. I'm guessing that means using six starters to try and fill the 1050 innings. This is probably viable assuming no injuries, but if any pitchers get hurt you probably are going to want to do more spot starting and not have to use your rotation every single start out (otherwise, you'll end up killing your ERA/WHIP with bad starts anyways). Since you'll be "out" of roster spots, this will mean that you'll have to get rid of a reliever(probably 2) in order to reach that roster limit.
So I probably wouldn't use this strategy; at least not to start. it's much much more valuable in a league with a smaller innings pitched limit.... The other option you would have is to not bother trying to reach your IP limit, but by doing this you're going to hurt you Ws and Ks and cancel out any advantage you would get by using your MRs. It's a viable strategy, just not one I would go with if I were you....