Ya I hate the fact that the bolt kits from the hot rod shop seem like they are a 1/4 inch to short. No room for lock washers. Im sure you could get those in 1/4 inch increments
That reminds me; there are two bolts (shown below) - out of the 12 used to bolt a stock intake manifold to the cylinder heads - that cannot exceed 1" length.
If a longer bolt is used, the tip will contact the adjacent push rod and bend it - or at least restrict it's motion. Use 1" bolts in these holes (that is; 1 inch as measured from under the shoulder of the bolt head to the tip of the threads):
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Note the proximity to the push rods:
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I
think that 1" is the max for the bolts indicated above and the others can be 1 1/4".
But it may be the case that 1 1/4" bolts are okay for those two - and you can use 1 1/2" for the rest of them. Best to check for yourself and not go by me.