No, I've been running without a kick down hooked up for 18 yrs. I did pull it out a bit and hose clamped it in place, in my lightweight t-bucket it makes the trans shift at different rpms depending on how far you pull it out.
No kick Down for Me with Blower, Really None of my None stock rides have a Kick down hooked up . Listen to engine RPMs & Tone of engine, & feel , You will know when to down shift
If your blown 454 makes any real power, you will have trans breakdown rather than kickdown issues. You don't have to run kickdown, it just makes it downshift quicker than relying on the vacuum modulator.
For me with Roots Blower , all was Used a stock case Pg ,400 with mods with out a Super bel , in 500 range of torque , Then adding Bell , then after market PG case , 400 strong Gm case 50/50 on stock bell around 2,500 -3,100 Pd Vehicle , I have had pretty good luck with 350 Gm case over years with some mild up grades , Not Extreme . Then Experimented Gm full case, B sbc 10 psi on 10:5 :1 piston , 4,000 converter No trains brake on 315 Radial , 2,800 ish pd, 6,300 rpm ,3 passes on street , Maybe be just old bad thin case @ bell . Now aftermarket case ,4L60 parts & other up grades . So Look @ Torque #s traction , weight.