Insurance denial!

[mysticclam]

Hey guys, im converting a 1980 3.3 straight 6 stang to 302 power. My insurance agent says farmers wont write me a policy on it because its a modified vehicle. Where then can i get insurance? What happens if i just didnt tell the insurance company and i get in a wreak, could i be denied coverage. What makes it worse is i cant even argue the car came with that motor factory because 1980 was a 255 (shudder) year.
Im worried this is gonna get me in trouble with the EPA too, but hang em, im using a 1970 block so im screwed if they check. Plan on running a clean setup with cats so im thinging they will never look that close.