Purchased a 91 Camaro with 454 swap already complete. Went for road test (approx 30 mins) made purchase and trailered home. First ride off the trailer she ran up to 250 degrees and was venting out the overflow once parked. I pulled and tested the radiator cap, thermostat, and water pump. All seem to be in good working order and opening and closing appropriately and flowing properly to include radiator and all hoses. Car has large aluminum radiator with dual electric fans. Motor is backed with a turbo 400 and previous owner tells me it is a 10.5:1compression build but knows nothing about the internals. I did a block test on it and no signs of compression gasses in coolant system. Timing was at 0 and idling about 1100rpm, Adjusted timing to 16 idle and about 36 at throttle. Idling about 800rpm. ran up to about 210 idling 15-20 mins and 230-40 after a ten minute drive. Where do I go from here? Also have minor smoking from driver side valve cover breather

Air dam is installed, dual electric fans running full time, radiator cap seals appear new and passed pressure test releasing spring at 16lbs

Moving from cooling to fuel... upped the primary jet from 76 to an 80 and no change. It’s at 16 degrees initial timing without vacuum advance ( previous owner never used it but I think I’m going to install a line and see if she likes the extra timing). Manifold is only pulling 1 mm/hg vacuum at idle, jumps to about 10 with hardly any throttle. Any thought on a/f and timing causing this overheating issue?