You need “racing triple” chainring bolts as here:
https://www.amazon.ca/DYNWAVE-Cranks...xpY2s9dHJ1ZQ==
if this long link doesn’t parse correctly, use my original search term which was “racing triple chainring bolts.” This particular listing seems to be for three sets, one each of single, double, and triple, all for one suspiciously low price. But it’s the long triple ones in the upper left that you want.
And yes you will need a longer BB spindle, (...or a BB with a longer spindle if you have a cartridge), unless you are able, as suggested, to fit the large ring outboard under the crank, and if the front der will swing out far enough to reach it.