Should I replace the stock 360 intake?

Those cast iron intakes are very hard to beat for what they were designed for and what they were designed AFTER. They are basically the same as the 1971 340 intake, but with the EGR added. They flow extremely well. People have used them in stock eliminator for decades and WON with them. A LOT. If all you are wanting is a cool truck to cruise around in, that intake will be just fine. If it was my truck, I would even build the engine back bone stock. They were pretty stout like they were. SO stout in fact, that in 1978 the Lil Red Trucks were the fastest production vehicles in the domestic market, even beating the 78 Corvette. It's true. Look it up. lol Course the Vette in 78 wasn't very strong, but still to get beat out by a truck was pretty embarrassing.