I haven't tried this, but I would say no. The command reference states the 501 and 506 can be a eVPN client OR eVPN server.
From the 6.3 comand reference:
The PIX 501 and PIX 506/506E are both Easy VPN Remote and Easy VPN Server devices. The PIX 515/515E, PIX 525, and PIX 535 act as Easy VPN Servers only.
The PIX 501 and PIX 506/506E can act as Easy VPN Remote devices or Easy VPN Servers so that they can be used either as a client device or VPN headend in a remote office installation. The PIX 515/515E, PIX 525, and PIX 535 act as Easy VPN Servers only because the capacity of these devices makes them appropriate VPN headends for higher traffic environments.