You would not regret the 440 crank. You would have to cut a 440s counterbalances with the shorter 400 rods or the pistons hit. Not every shop does that..but it can be done in a lathe. If you don't cut the counterbalances w a 440 rod, then more time has to be spent grinding on the block so the crank can turn, the exception being some of the early 230 blocks, they seem to have more clearance. Cutting the mains to b takes a machine shop bit longer but usually isn't real expensive. Aftermarket stroker cranks is what most now do.
I would suggest having the valve guides cut for viton seals and get new valve springs that match the new cam. It's a simple procedure, you can even buy a cutter and do it yourself if you want.
Several convertor companies have stepped up their game doing tight convertors. IMHO a 9 1/2" is a great size for the street..we now have used 5 of them. They have great street performance because they are tight, but leave the starting line more like a racecar, PTC is probably the most reasonable priced custom brand, we also have a ultimate, FTI and a dynamic. Several companies market their convertors as 9"..but when you measure they are actually 9 1/2"???marketing I guess.
For 3.55s a hughes 24-2500 convertor is OK for a budget built. They are a looser built convertor so 2500 is about all I would want with your combo. The other entry level over the counter brands I would stay away from.
I would nail down your plan for the engine internals before you buy a cam. I would try to buy old stock lifters if you can find them.