The clutch pedal assembly will be difficult,only because there are bolts which are hard to get to,even with the dash out.You should use the complete 5 speed pedal assembly though,instead of cutting the brake pedal to clear the clutch pedal.
You can order Pre cut lexan through FAL..I usually go to the big hardware stores and buy sheets of 1/8" thick lexan(lowes,home depot).It will be alot cheaper to cut them yourself.