I don't think 60 feet will harm anything. In high school a friend bought a four door hardtop 66 LTD with a 390. He liked the sound of open headers like the older fast guys had but of course had no money. He pulled the exhaust manifolds off anyway in anticipation of getting headers and of course broke off most of the upper bolts, Even if he had headers there would be no way to attach them.... so he drove it, for months, with no exhaust manifolds whatsoever. Sure it did wreck the engine eventually or perhaps it was the frequent 6500+ rpm blasts in first gear at highway speed that wrecked it.
The cool part (besides the many police stops) was it made flames out the ports! Woohooo, just like Don Garlits.