I assume you have the RAW files on a local drive.
Import them into Lr Classic, Export them as .jpg then Add them to the Lr CC ecosystem thru either/both Lr CC Desktop or Web.
Your Raw files stay safe so you can back them up to another drive as does a copy of the .jpgs plus you have a copy of the jpgs on the cloud for whatever you would like to do with them from there.
That aside: IMHO I see NO good reason for sending files to the cloud that are already on my computer system or sending photos shot with a non mobile camera (DSLR). Lr classic or Camera Raw is ideal for those files. Lr CC (cloud based) is for MOBILE images.
Thanks for the reply. I like to have every photo I've ever taken available on the cloud and across all my devices, no matter what device was used to take it.
I may find myself wanting to show someone a picture I scanned of a family member from the early 1900s or a photo I took skiing with a cell phone or a waterfall I took with a DSLR. Having them in the cloud, allows me to do that.
I would love to be able to use a mobile device for all my editing, but if I go on a DSLR-specific photo shoot and come back with 200 photos, it's not practical to upload them to the cloud with the new program. Editing in Classic and exporting to JPG and importing into the new CC as you suggested is probably the best option. Thanks again!