which engine in my 74 swinger

Hey guys. I'm restoring a 74 swinger. It has the original 225 slant 6 and auto Trans. They both have 7k after the rebuild. I'm almost finished with the all the body work and I'm ready to get it back together. I usually restore everything completely original, but on this one I'm going to have some fun. I want to pretty much have a sport in a swingers body. Any suggestions on which motor I should go with? I'm wanting to have as much speed and h/p possible. I have a'53 241 red ram but that baby hemi only has 140 stock. I want to keep the value up while having a beast at the same time. I am between a 340, 360, or 440. The hemi is beautiful but just not enough power for me. Any suggestions would be much appreciated. Thanks