Saints be praised! What manner of Reagan will he be, this son of Ireland returning to the Emerald Isle this fall? Will he be Ronald Wilson Reagan, the president, or will he be Ronald Prescott Reagan, the First Son and ballet dancer recently turned free-lance journalist?

On assignment for Signature magazine, Ron Jr. will be searching for the Reagan family roots in County Tipperary any day now, says Signature editor Horace Sutton.

Sutton says young Ron worked out his trip with the Irish Tourist Board and that details are top-secret because he doesn't want the paparazzi dogging his trail. That may explain some of the confusion in Ballyporeen (population 300).

Everybody there thinks it's Ronald Reagan, the father, who is coming to town around Oct. 5 to put them on the world map. In happy anticipation, they have turned a children's playground into a landing pad for Helicopter One.

Recently four "lantern-jawed security men" (as a London news hawk described them) visited the Ronald Reagan Lounge in Ballyporeen and had a quiet chin wag with the publican, John O'Farrell. Secretary of Health and Human Services Margaret Heckler, who spent her childhood not far from Ballyporeen, recently materialized there as well, reportedly signing the pub's visitor's book, "Until we meet again--with Ronald Reagan."

Meanwhile, across the Irish Sea, the official folks in London are reportedly less enchanted over any forthcoming visitation, if not outright "dismayed," as Fleet Street printed it.

Newspaper writers, perhaps not with their own family roots in the old sod, have pointed out that a Reagan visit during the current troubles in British Northern Ireland would intrude into the delicate argument over whether all of Ireland should be under the rule of independent Dublin.

White House schedulers have Reagan--the president--in Washington on Oct. 4 to welcome Karl Carstens, president of the Federal Republic of Germany. He's due on a state visit to mark the 300th anniversary of the arrival of German immigrants in America.

An Irish Embassy official here had a diplomatic response to the suggestion that a more appropriate date for a visit by President Reagan would be next March, on St. Patrick's Day. "That's a bet I wouldn't wager a potato on," said the diplomat.

Be that as it may, villagers of Ballyporeen remained convinced that it will be President Reagan stepping onto their new playground-helipad Oct. 5 to visit his grandfather's old home.

In the early 1850s Michael, the grandfather, quit Ireland for England where he married and began his family. Then he headed west across the water, off to the promised land with countless countrymen driven in flight from the lingering suffering of the Irish potato famine.

The immigrant trail led eventually to Dixon, Ill.--now regarded by Dixonites as President Reagan's official hometown. He grew up there though he was born in Tampico, Ill., on Feb. 6, 1911.

The Reagan family home in Dixon is being restored at an estimated cost of $100,000 by a group of Illinois businessmen and supporters calling themselves the Ronald Reagan Home Preservation Foundation.

The foundation soon will go national for tax-deductible donations to finance the restoration. The work is scheduled for completion at the end of October, and the foundation has hopes that President Reagan will be on hand for the public dedication.

The restoration will probably put the house in a condition it never enjoyed when the Reagan family lived there. As Neil Reagan, the president's older brother, recently told committee members: "If you really want it true to life you wouldn't repaint it because it always needed painting when we lived there."