Daver: if you ask that much to not make mistake with ruining handling .. one mistake is already done. You should have bought square wheel setup (around which suspension/brakes/electronic nannies of our cars were designed), not staggered. With yours you'll get more understeer with front plowing out. I'd also wouldn't go for that wide wheels at least if you plan to keep NA power, as even stock sized non-premacy tires will have more grip. As result with planned 235-265 tires at least ease of power oversteer will certainly be gone. Yes, one can still intentionally loose grip on much grippier tires, but most probably at higher speeds and with much more aggressive maneuvering (further accented by extra understeer of staggered setup). BTW, side gain for square setup is ability to save on tires (handy in long run during your planned use for few years and especially if you plan quickly burn rubber on some track days
) by rotating them according to wear front-rear, and easier to get just one size/type of replacement wheel if you damage it.
+what you yourself have quoted about overlowering. To not overspend on correcting what can be botched with too much drop it's wiser to be choose more reasonable drop below 1", which should be somewhat safe. My own choice is to not lower at all due practicality reasons, but as you mentioned "4x4 gap" it probably bothers you enough to have some drop anyway. Better do that within 1".
Worth reading first post of
this thread.