I don’t know much about drifting, but it’s my understanding that you NEED HORSE POWER! So as everyone has already said the easiest way to accomplish this is with a V8 swap. If you’re set on running a inline 6 my suggestion is to upgrade to the 300ci, (they produce plenty of torque) you can find performance parts such as 4 barrel intakes and headers. If this is the route you chose check out Clifford Performance. https://shop.cliffordperformance.net/Ford-240-300_c3.htm
A 300 weighs as much as all iron 302/5.0 and due to its length, likely more difficult swap. Plus cost to build to performance specs, likely 2 or 3x more costly than 5.0. With aluminum heads, intake ect, it's possible to reduce weight of 302 to around 400 lbs.
Drift cars like tons of extra engine rpm and wheel speed too. Not the inlines forte' at all. Buy a small V8 and cam it up to about 7,000-7,500 rpm and go have fun.