Edelbrock / RHS heads, or go BIG block and put it to bed!

You guys are batting a thousand on all your advise !!! Thank you !!!
2 years ago I put a built up 360 in my 68 DART. 17,000 miles on the motor now and pushing 275 hp 300 trq at the wheel with auto 904. 13.50 @ 100mph 1/4 mile. I WANT MORE POWER ! Please help !

A) Eddy alum heads will give me 75 hp for a cost of 2500 installed all parts
B) RHS are cheaper but will they give me enough help
C) ? changing the heads with 17,000 miles to high for head change ?
D) Motor builder offered a 440 long block with aprox 500 hp for 6,000 $

I need all input please. I want to know what you guy would do.