I had a little experience with those the last few years. And of course I have my opinion.
First, don't buy a Chinese HEI, I did, the pick up coil came loose and it beat itself to death. The groove for the snap ring was not machined correctly.
Second I bought a MSD "ready to run" distributor. It isn't. Just google ready to 'not run'.
Has a shaft larger that stock, if you have a melonized or payed $70 for a bronze gear, or a polymer gear that you payed $125 bucks for, it wont fit on the MSD's larger shaft diameter. That means forking over another $125 bucks for another gear.
Mine came with a pre bent shaft and everything under the cap was pre-corroded. Saved me the trouble of bending the shaft and getting it corroded myself. Just google MSD corroded distributor.
If you can, get a stock HEI and rebuild it using stock parts. You will have a better distributor than you can get from China or MSD!
Just my opinion.
You may be able to get a good aftermarket HEI, but phone or email the manufacturer/vendor and find out where they are made.
DUI says there's are made in the US but I've no experience with those,
FWIW