Ram Horn manifold too deep for studs

[KyFarm]

I bought some Flowtech Ram Horns to put on the 383 I'm working on. Went to test fit the manifolds and spark plug wires today before engine goes into truck and turns out the studs sent to me are way too short.

Manifold is 2 3/8" thick, 3/4" deep into head, gaskets, washer, nut and a little exposed thread gets to about 4". Studs are only 2 1/4" long.

Holley (flowtech) were a bit perplexed, said they must have changed the casting which seems strange, the bolts are about 2" too short!

I thought I would be able to find 4" manifold studs on the internet but at the moment I cannot. If anyone knows where I could get some I'd appreciate it.

Otherwise, Can anyone recommend some shorty or block hugger headers for a small block in a '69 K10.

Thanks for any help.