Lol. Oh boy. Well, here we go...
So, I've pretty much figured Goku's Kaioken Kamehameha to be an amplifier of around 1.25x. This is reasoned because it is a "pathetic" amp based on Piccolo's own assertions while fighting Cell, but also from a logical standpoint. It all starts with Yamcha. Yamcha's Wolf Fang Fist should at least be around a 1.1x boost. He uses a Wolf Fang Fist 2.0 as well, which should be upgraded from that. Let's say 1.2 to be fair. All in all, Yamcha still favors the Kamehameha as his big attack vs Tien, letting us know it's superior to Wolf Fang Fist 2.0. Let's say Original Kamehameha is 1.33x. Kamehameha is never suggested to be pitiful or pathetic on it's own, it's supposed to be able to decide a fight of equal level according to Roshi. However, there is Tien's Kamehameha vs Jackie Chun which suggests there are other options. Anyway, a reasonable blast should be a 80-100 gap imo, which is also a good space for a standard solid power up. It's significant enough to where you can completely whoop someone's ass, but not really take them out without any effort. I've always felt the 2.22x blast for Goku was ridiculous in the Saiyan Saga and it is, it's completely not necessary and not even factual based on the characters's own statements. So, a good standard, not Kamehameha amp is probably 1.2-1.25x or so. Which falls in line perfectly with...
(Masenko = 2,800> Enraged Gohan > Piccolo ~ 2,000)
With a 1.25x boost, Gohan ends up around 2,400. If we do this again for the Masenko used on 3rd Form Freeza, we end up with harmony within the levels that constitutes Gohan being solidly above Piccolo, but not tremendously so.
Same goes for Goku's Kaioken Kamehameha.
( Freeza 50%+ ~ Goku's KKx20 Kamehameha > Goku KKx20)
As we can see, Cell's Kamehameha is laughed off by Piccolo. It's quite possible that Cell has Goku's KK Kamehameha cells, which would be his worst Kamehameha. Which makes sense within the scope of the story. Consider this...
(Goku's Kamehameha vs Raditz) vs (KKx20 Goku's Kamehameha vs 50% Freeza)
Even Krillen goes on to talk about how ineffective the Kamehameha was against Freeza.
Ok, so now getting to Vegeta.
Even accounting for Goku's weakened Kaioken Kamehameha multiplier, Vegeta's amplification is still stupid strong. He is even surprised that a stronger Goku can match his blast. Vegeta has always had a high amp apparently, seems to be one of his trademarks that differentiates himself from the other two Saiyans in his crew.
So all in all, I have a hard time seeing Vegeta with such a weak blast, when he clearly intends to finish the fight against a much stronger opponent. I think the blast has to at minimum be at Reecome's level, if not superior.
I apologize for the jumbled mess, but it's much too hard to organize and present the information in an orderly fashion. Good luck reading all that!