Not sure what year LC mcylinder to use, but best bet is to buy the one from Marlin for $129 (it's Aisin OEM). I couldn't find any locally that included the reservoir (which is different than your stock one). The reason for going to a bigger MC is to push more fluid in cases where you have larger piston front calipers (ie using the V6 style 4 piston calipers or going to disc in the rear). However, on a stock brake system, the larger MC will mean that you have less pedal travel for the same amount of braking, not really a strong reason to do it, but if you plan to upgrade to the LC vented rotors & larger calipers in the future then might as well go to the 1" master now. If you simply have squishy brakes, an easier fix might be to flush the system to get rid of the old fluid, refill and bleed.