I have swapped out my standard hood for the 400 version. I am considering putting the 350 emblems on the 400 hood where the 400 emblems are normally located. I know this is not correct but I am just wondering if it would work (i.e. do the 350 emblems have the same contours as the 400 emblems). Has anyone done this?

350 emblems do not fit. You need to drill holes. May look awkward as the 350 are thicker and thud raised higher.

I put 350 emblems on my repro 400 hood,I didn't want to drill holes so i cut the tabs off and used 3m double sided tape.If you have the holes already for the 400 emblems just cut off the tabs on the 350 emblems and position them soo they cover the old holes

Did the 350 emblems fit the contour of the hood? Do you have a pic?

Tape i used was fairly thick so it helped fit the contour,I can get a pic tomorrow if you need one.

I did the same as Harry but went one step farther. I ground down the posts on the 350 emblems and continued to grind some of the back off of them so they would lay flatter. Then I mounted them with 3M tape. Last year I removed them to detail the hood and they were very well bonded yet after 4 years. My hood was never drilled for emblems so that was not an issue.
No pics at this time but I can ges some if needed.

I know there are some who think these hoods should only be on original 400s but I love the look and I'm obviously not trying to fool anyone. I have been asked at shows if it was an option or if it was dealer installed.

I put 400 emblems on my 326 hood. I made little cardboard templates of the emblems by poking holes in the card stock for the pins, then tracing and cutting. Then I placed the emblem replicas where they looked good and covered the existing 326 emblem holes and marked the new holes for drilling.

Don't mind the dust but here's two pics,If i did it again i would use a thinner tape but it looks okay..

Looks good dude!

looks good ,and as 350 were on a 'flat' hood and therefor more tilted than 400 emblems , these will 'get up' there even more