Re: 460 intake
You could and then deal with the resulting engine knock by retarding the timing about 4 degrees. You will lose MPG and performance.
The EGR only is in play at part throttle and does not have any effect on full throttle operation so just get the correct maifold, and comply with emission laws.
A high mileage 460 from that era may need more than an intake to make it perform imo.- BA
2001 Grand Marquis LS, 25K miles mint (edit; now 56K miles) Finally a vehicle with NO LEAKS !