Well the 352 is not a sideoiler casting. Those were specific to the 65 and later 427's. Your 352 block is a topoiler and who ever told you it's a sideoiler casting might have been thinking of a Y block which was the precurser to the FE series of which your 352 is from. Y blocks are where Ford first used the sideoiling concept. Your 352 has a 4.00" std bore and a stroke of 3.50". The heads were also used on 390's also in most years so that's true. The 352 crank is nodular iron and differnet from a 429 3.59" or 460 3.85' crank. Those are "385" or "Lima" series engines as they are known. The two most common upgrades to a 352 are the 390 or 410. You can safely overbore your 4.00" 352 block to a 4.05" std 390/410 cyl bore. Get either a 3.78" stroke 390/427 crank or a 410/428 3.98" stroke crank. You need a good set of short FE rods to use the longer stroke cranks. Pistons are plentiful for these combos in cast, hyper or forged versions. Budget should be noted. The 390 upgrade is the most cost effective. A good 390 crank can be found for under $100 in most cases. The 410/428 cranks are a little more expensive at $300 needing to be turned and up to $600 finished ready to go. The heads you can run stock if budget is tight. Or have them ported and install some CJ size valves. A nice cam and new valvesprings to match. I'd suggest a set of adjustable rockers as they make life easy on pushrod lenght issues. So you can do a nice street/strip 390 build or go wild into the strokers with Scat 4.125 or 4.25 cranks and Edelbrock, Dove or blue Thunder heads and intake. Proceed with wallet open.....carry on.