Holley 4224 vs. 1850 needle and seat ?

[427dart]

While looking online for spare needle and seats I noticed the R-4224 660 takes a different part no. seat assembly Holley 6-508.
The other side hung carbs like 1850 take a Holley 6-506. Both are adjustable and have same .097 metering hole.
Only thing I see different is the 6-508 has the small spring clip to retain needle to float.....is that it and could you use the one without clip if you had to?