The heads of the nation's largest mutual fund complex and of one of the largest “third market” brokerage firms asked the Securities and Exchange Commission today to block what they charged were the attempts by the New York Stock Exchange to become a nationwide monopoly. S.E.C. Is Urged to Block Proposals of Big Board

The heads of the Roman Catholic and Protestant Episcopal Dioceses will talk to each other's flocks next week. Pichard Cardinal Cushing will address the Massachusetts Clerical Association Monday at Trinity Church. The association is an informal organization of Episcopal clergymen. The Right Rev. Anson Phelps Stokes Jr. will address the League of Catholic Women at the Vendome Hotel Friday. Clerics to Exchange Talks

the Heads Up Chorus, and the Haywire, a creature with four arms and four legs that spins on the dance floor. The show also includes a puppet-making demonstration. Performances are on Saturdays and Sundays at 2:30 P.M. Through May 16. Mazur Theater at the Asphalt Green, 555 East 90th Street, Manhattan. Tickets: $8. Reservations: (212) 539-3004. ''GUYS AND DOLLS,'' the Frank Loesser musical, based on the characters of Damon Runyon, will be presented by New York Youth Theater, with a cast ranging in age from 11 to 18. Fridays at 7 P.M.; Saturdays at 2 and 7 P.M.; Sundays at 3 P.M., at Central Presbyterian Church, 593 Park Avenue at 64th Street, 6th floor. Through May 23. Tickets: $12. Reservations: (212) 888-0696. FOR CHILDREN

the Heads Up Chorus, and the Haywire, a creature with four arms and four legs who spins on the dance floor. The show also includes a puppet-making demonstration. Performances are on Saturdays and Sundays at 2:30 P.M. Through May 16. Mazur Theater at Asphalt Green, 555 East 90th Street, Manhattan. Tickets: $8. Reservations: (212) 539-3004. SPARE TIMES

the Heads Up Chorus, and the Haywire, a creature with four arms and four legs who spins on the dance floor. The show also includes a puppet-making demonstration. Performances are Saturdays and Sundays at 2:30 P.M. Mazur Theater at Asphalt Green, 555 East 90th Street, Manhattan. Tickets: $8. Reservations: (212) 539-3004. FOR CHILDREN

The heady nomenclature suggests that something pretty frenzied has been going on in perfumes. And it has.