depends on how 'close to the rad' the fan is, needs to be 1/2-3/4" and fairly well centered on the rad - but a 350 can easily run 210 with no problems .... also, if you have the stock 37 rad, it will use a 0-pressure cap, which isn't good enough for a SBC, which will run hotter [with more pressure] than the rad can stand
a shroud might help if the fan is more than an inch back, but you really need a pressure cap [at least 7#], which will require changing the fill neck on the rad, and an original rad might not take the necessary pressure long
Bill
