A swapped motor into a Honda (or any other make/model) puts you in SCCA's Prepared class or SM class for auto-x. If you want to race wheel-to-wheel then you'll be in their Production class.
As for not being competetive, that's utter BS. Here is a list of the last 30 years winners in SCCA E-Prepared:
E Prepared:
2004 Chris Dorsey Colorado Springs, CO Honda CRX
2003 John Thomas Tampa, FL Honda Civic
2002 John Thomas Meridian, MS Honda Civic
2001 John Thomas Meridian, MS Honda Civic
2000 John Thomas Tampa, FL Honda Civic
1999 John Thomas Tampa, FL Honda Civic
1998 John Thomas Meridian, MS Honda Civic
1997 John Thomas Meridian, MS Honda Civic
1996 John Thomas Meridian, MS Honda Civic
1995 John Thomas Meridian, MS Honda Civic
1994 John Thomas Memphis, TN Honda Civic
1993 John Thomas Memphis, TN Honda Civic
1992 Howard Wolf San Jose, CA Ford Escort Mexico
1991 Tom Anker San Jose, CA Datsun 510
1990 Chuck Noonan Barre, MA Honda Civic
1989 Chuck Noonan Barre, MA Honda Civic
1988 Chuck Noonan Barre, MA Honda Civic
1987 Randolph Welch Salt Lake City, UT Datsun 510
1986 Randolph Welch Salt Lake City, UT Datsun 510
1985 Randolph Welch Salt Lake City, UT Datsun 510
1984 Chet Hansen Fresno, CA Austin-Healey Sprite
1983 Tom Bootz Evansville, IN Datsun1200
1982 Tom Bootz Evansville, IN Datsun1200
1981 Tom Bootz Evansville, IN Datsun1200
1980 Howard Wolf San Jose, CA Fiat 850 Spyder
1979 Craig Way San Jose, CA Fiat 850
1978 Gary Gooch Union City, CA A-H Sprite
1977 Gary Gooch Union City, CA A-H Sprite
1976 George Phillips Richmond, IN Triumph Spitfire
1975 David Lacy Houston, TX MG Midget
1974 David Lacy Houston, TX MG Midget
1973 Chet Hansen Fresno, CA Austin-Healey Sprite