If you liked the 280 purple shaft in a 318 you will love it in a 360
while dated it is still better than any chevy grind out there
For info: a 280 mopar has more seat duration than a 285 Comp or other cam rated at .006 and more than a 290 Crane or any White Box cam rated at .004 or by the SAE method the mid 9 compression should be fine with that big cam
hope you kept the lifters in order, if not get them refaced (budget build) new timing chain if needed and new springs that lift - well I'll ask the group if stock 340HP springs would work they can be had about as inexpensive as anything- and good viton stem seals the center two exhausts do get hot
if you have the 280-280 version you should have headers
check your rockers for wear- channels where the stem was riding I would not use worn rockers on new valves
thin lash caps will prevent grooving the rockers but should not be a problem with moderate valve spring pressure
If you need new lifters get Magnum/AMC and oil through the pushrods to help with pushrod push through the lifter cup problem