This will vary depending on what rate springs are being used and at what installed height.
Stock diameter Crane springs (p/n 99839), w/90 lbs on the seat, and 280 lbs. open pressure are good for .575"-.580" max lift. I would not try that much lift w/OEM 049 springs- but who uses those, anyway?
I think it would be really hard to say with a stock set of springs. Even if you knew what they could handle stock, after 25 years of use, they may not be up to that task today. If you are buying a new cam, I agree with just buying a new set of springs.
The other issue would be piston to valve clearance. this depends on a bunch of factors. The best thing to do would be to try to check it. For reference, I have a set of 049 heads and a 248 254 @ .050, 277 284 advertised duration .600 lift cam with no issues. My pistons have valve reliefs though.
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