Yeah, pretty much what
@DBZMLP12345 said. Even if we ignore Goku's claim he can use KKx10 on Namek, and say he is still capped at x4, those would be the conservative numbers.
Although he outright says he can use kkx10 while going to Namek, uses it easily vs Frieza, and even a higher level one, and there is no contradiction to him having kkx10 either, so I would still use x10 instead of x4 for base Frieza saga Goku's boost as it is what is indicated by Goku himself. Like I said, ignoring his statement about kkx10 is like ignoring Cells statement that he can SS bust, unnecessary and contradictory to the narrative of the manga.
The list using kkx10 looks like the following
(this is the most accurate imo since tbh there is no reason to dismiss Goku's statement that he can use kkx10)
Goku/Piccolo (Beginning of Z) =
0.745c
Raditz/Saibaman >
0.745c
Piccolo/Tien/Yamcha/Krillin/Chaiotzu/Gohan/Yajirobe (Saiyan Saga) >
0.745c
Nappa >
0.745c
Goku (Saiyan Saga) >
0.745c
Kaioken x2: >
1.49c
Kaioken x3 >
2.235c
Kaioken x4 >
2.98c
Vegeta (Saiyan Saga) >
1.49c
Zarbon/Dodoria/Cui >
1.49c
Recoome/Burter/Jeice >
2.98c
Goku (Namek Saga) >
7.45c
Kaioken x2 >
14.9c
Kaioken x3 >
22.35c
Kaioken x4 >
29.8c
Kaioken x10 >
74.5c
Ginyu >
7.45c
1st Form Frieza/Vegeta (Zenkai, rested up) >
29.8c
2nd Form Frieza >
74.5c
Piccolo (Fused with Nail) >
74.5c
3rd Form Frieza >
74.5c
Vegeta (Zenkai, healed by Dende) >
74.5c
Goku (Zenkai, healed from Pod) >
74.5c
4th Form Frieza (Casual) >
74.5c
Kaioken x10 >
745c
Kaioken x20 >
1,490c
50% Frieza >
1,490c
100% Frieza >
2,980c
SSJ Goku >
3,725c