Most radiator systems with old style upright radiators used lower temperature,generally around 140 degrees. Baseboard fin tubing uses higher temp around 175-180. I believe you can use the infloor pex tubing at that temperature. As Harold says though, put it on its own zone with a separate pump. The pump will turn on the boiler and the zone valve when the t-stat in the room calls for temp.
Good Luck
Raymond VinZant