The premise of your scenario is quite similar to the time Polian traded up for Ugoh except he gave up a late 2nd and 1st the following draft in order to obtain an early 2nd. I'd do something similar with one of our early 2nds.
Even if Chubb is gone then one of Allen, Mayfield, Barkley or Nelson will be there at 6, and certain teams will bid on them until the selection is due. Our draft position is still very good, just need to let it play out.
The Colts gained a sizeable premium moving down from 3 to 6, however this trade is almost equal value as the 6th is worth 1600 compared to 1592 for the Cards' picks. Considering there are seven so-called franchise talents in this draft (4qbs & Chubb/ Barkley/ Nelson) then there needs to be a premium attached to #6. I'd require Arizona's 2019 1st in addition to 15, 47 & 97.
Regardless, I like your picks minus Goedert in the 2nd.
Based on production thru 8 seasons:
Antonio Brown/ Marvin Harrison :
Rec - 733/ 759
Yds - 9,910/ 10,072
Avg - 13.5/ 13.3
Yds/g- 86.2/ 81.35
TDs - 59/ 83 (This is what separates Marv)
20+ - 146/ 131 (Adv Antonio)
40+ - 33/ 30
My comparison is valid with exception to calling Antonio a "very poor man's Marvin," but I will revise my statement to reflect that Antonio is a lesser Marvin. All things being equal Marvin's ability to find the end zone elevates him above AB.