Mark Baron is the owner of Killa Grilla (aka:BellexInc). In 2018 I worked with Mark in having him create the stainless steel cooking grates for those old flat top kettles. Below are the part numbers for the three grates that were offered for sale on his site at that time.
KG9245_(2 door flip up gates) 24.5 Cook Grate
KG8245_(1 door flip up gate) 24.5 Cook Grate
KG6245_Standard 24.5 Cook Grate
Pretty sure that Mark will custom make you a cooking grate for your flat top 26er as he has made me multiple custom SS grates in 18", 22" and 26" size. Here is his contact information.
Mark C. Baron
Bellex, Inc.
2009 Johnson Industrial Blvd.
Nolensville, TN 37135, United States of America
website: BellexInc.com and KillaGrilla.com
M(615) 533-4019
email: bellexinc@msn.com