The stock ECU will keep up with an average 250 hp (crank) Stroker, after that you'll want to look into aftermarket fuel managment, to help make the power you will need both fuel and spark custom tuned to your engine. Plan on 98 octane and 11 to 1 compression (or better use E85 if available and even higher compression).
Besides that I can think of several things that will help meet the 300hp goal. First of all realize you will be sacrificing some long term reliability to make more power. Don't expect a max power build to last 200K miles... 100k maybe but the number gets lower the more power try to make. Build with tolerances just loose of factory specs, looser tolarences = less friction within reason (in other words where a range is specified, .010 to .014 use .014 or the looser of the two and spend the time needed to actually GET that tolerance the same from bore to bore or bearing to bearing. get the bores done with a torque plate, and pay your friend (or bribe him with beer) to get your bores as perfectly matched to the pistons you will use (not a mock up set) as possible. Need I mention keep the Beer away until the days machine work is done? Balance everything. It shouldn't take that much to get any 4.7L engine into the 300 crank hp territory... Obviously flip the piston orientation, use bronze valve guides, a 3 angle valve job, as big an intake valve as you can fit using an offset guide. hand polish all your journals, including cam, and cam lobes, use a fairly radical Cam. use a big ported throttle body, the 99+ intake, and make sure the intake is getting OUTSIDE air, not engine bay heat (either through some custom ram air ducting or a cowl induction hood). If you throw in all the racing inspired build tricks you practically can it should come away with more than 300hp without any crazy parts or drastic measures (like offset ground cranks, or big overbores).
300 is only 40 more than HESCO's off the shelf 4.7 Stroker... I bet a good porting job, a windage tray and close attention to all the build factors and machine work I mentioned above would make that 40hp with ease. All that without spending crazy money on bolt ons, or power adders. The close attention to detail and tolerance machine work will be the big expense, but since you have a buddy