You're right, the DOHC B234F should be every bit as quiet or quieter than the SOHC red blocks. It should also run a whole lot smoother. Having said all that, it's quite normal for the B234F valves to be noticeably noisy right after starting, especially on a car that does mostly city driving. Even if you religiously change the oil at the recommended 5K Mi (8K Km) service interval, the hydraulic lifter passageways easily start to get a bit plugged with deposits and take increasingly longer to pump up on a cold engine. Using a high quality oil of the recommended weight, more frequent oil changes based on a time and operating conditions basis, and most especially more higher-rev highway driving all helps to minimize such deposits.

You're probably well aware that many brickheads and pro mechanics would prefer to stay clear of a B234F because it's an interference engine that has earned a bit of bad reputation for timing belt failures leading to top end damage, often considered fatal (replacement cylinder heads are difficult if not impossible to source these days). It's not so much they're a bad engine, just they're not as bullet proof as a B230F. You need to replace the belts, tensioner, idler pulleys, oil seals and timing covers before they become a problem, not after. Changing the timing belts is also a fair bit more involved than your B230F (see the FAQ). If there are no detailed service records then factor in a cost for having to do it all now to be sure everything is okay.

They're also prone to oil leaks at the valve cover gasket and at the head gasket. Check for any evidence of an oil leak having developed below the head gasket in the area under #4 exhaust runner to just around the corner at the back. Valve cover gasket leaks at the bottom of the spark plug recesses often go undetected -ask if you can remove the plug cover so you can inspect the bottom of recesses doing a quick blot with a bit of paper towel wrapped on something thin to show any fresh oil

Now as for the car you're looking at, I would find a low mileage 740 in good condition very appealing even with a B234F if I knew it was well maintained and I was willing to keep it that way. Take it for a good run, or at least throughly warm the engine until the temp gauge is fully up. The valve noise should begin to improve within the first few blocks of driving and will be about as quiet as it's going to get within 1-2 miles. If it at least starts to quiet down then things will likely get better with more frequent oil changes and some good highway driving. A good old fashioned Italian tuneup can do wonders for a city slicker B234F, especially with an automatic. I would also definitely recommend running a B234F on synthetic oil.

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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now